v2.8.0-alpha.2

Release of 2.8.0-alpha.2

• Add Android 5.1 support.
• Enable auto delete of pending of message after a configured number of retry is exceed.
• Brought back HTTP client support for devices running Android v2.2.
• Fix inconsistency with message result API codes.
• Fix issue with sync to only one Sync URL even though multiple have been enabled.
• Re-activate donation button.
• Disable proguard minification.
• Fix issue with date format being null.
• Add Japanese, German and Indonesian translations.