chore(build): fix versioning and uploading (#10)

We previously were uploading the contents of firmwarebin/ to s3 which as it
turns out is a checked-in file that never changes. That is not what we want to
do.

Instead,
- Remove firmwarebin/ as a checked-in file
- Instead, use it as a directory containing the properly named build output
- Copy built hex files into firmwarebin using the same value as the version
string embedded in the build itself
- Make that version string generation actually work properly when running on a
checked out tag (which is a detached HEAD, which git show-ref doesn't like;
instead, there's a bit of logic to check if we have a branch and if not use git
describe)
- Upload tha actual fresh build to s3 instead
- Also, on tag, update the github release, since without the firmwarebin/
directory checked in it's nice to have somewhere to point to for stable builds
- Because we need to use git symbolic-ref and git describe, check out the
TRAVIS_BRANCH.

.gitignore

@@ -21,3 +21,5 @@ debug
 /win_install.log
 /linux_install.log
 /src/default_excludes.mk
+firmwarebin/
+gcc-arm-none-eabi-*

.travis.yml

@@ -12,22 +12,32 @@ install:
   - sudo apt-get install libc6:i386 libstdc++6:i386  
   - ./travis_install
 
+before_script:
+  - git checkout $TRAVIS_BRANCH
+
 script:
   - make clean build
 
 deploy:
-  provider: s3
-  access_key_id: $AWS_ACCESS_KEY_ID
-  secret_access_key: $AWS_SECRET_ACCESS_KEY
-  acl: public_read
-  local-dir: firmwarebin/
-  upload-dir: ${TRAVIS_BRANCH}-${TRAVIS_BUILD_NUMBER}
-  bucket: $HEX_BUCKET
-  region: us-east-2
-  skip_cleanup: true
-  on:
-    repo: Opentrons/SmoothiewareOT
-    all_branches: true
+  - provider: s3
+    access_key_id: $AWS_ACCESS_KEY_ID
+    secret_access_key: $AWS_SECRET_ACCESS_KEY
+    acl: public_read
+    local-dir: firmwarebin/
+    upload-dir: ${TRAVIS_BRANCH}
+    bucket: $HEX_BUCKET
+    region: us-east-2
+    skip_cleanup: true
+    on:
+      repo: Opentrons/SmoothiewareOT
+      all_branches: true
+  - provider: releases
+    api_key: $GITHUB_OAUTH_TOKEN
+    file_glob: true
+    file: firmwarebin/*.hex
+    skip_cleanup: true
+    on:
+      tags: true
 
 notifications:
   email:

README.md

@@ -2,7 +2,7 @@
 
 *This is an Opentrons fork of the open-source [Smoothieware](https://github.com/smoothieware/smoothieware)*
 
-[Recent Stable Build Here](https://github.com/Opentrons/SmoothiewareOT/tree/edge/FirmwareBin)
+A recent stable build can usually be found in the releases.
 
 Smoothie is a free, opensource, high performance G-code interpreter and CNC controller written in Object-Oriented C++ for the LPC17xx micro-controller ( ARM Cortex M3 architecture ). It will run on a mBed, a LPCXpresso, a SmoothieBoard, R2C2 or any other LPC17xx-based board. The motion control part is a port of the awesome grbl.
 
@@ -42,6 +42,14 @@ Please take a look [here](https://github.com/Opentrons/opentrons/blob/edge/CONTR
 
 Contributions are very welcome !
 
+## Releasing (for Opentrons devs)
+
+When you want to release a version of the smoothie software for subsequent Robot OS updates, just create a github release in this repository. Travis will automatically build the tag and post it to the release. 
+
+Note: You must create the github release first - don't create and push a tag from your remote. The release needs to be created for Travis to properly deploy the result.
+
+Once you've made the release, go update the [package in buildroot](https://github.com/Opentrons/buildroot/blob/opentrons-develop/package/opentrons-smoothie-firmware/opentrons-smoothie-firmware.mk).
+
 ## Donate
 We based our firmware off of the smoothie firmware which is developed by volunteers. If you find this software useful, want to say thanks and encourage development, please consider a
 [donation!](https://paypal.me/smoothieware)