Release 0.6.0

[mmroz]

Standards checklist:

• The PR title is descriptive.
• The PR doesn't replicate another PR which is already open.
• I have read the contribution guide and followed all the instructions.
• The code is mine or it's from somewhere with an Apache 2.0 compatible license.
• The code is efficient, to the best of my ability, and does not waste computer resources.
• The code is stable and I have tested it myself, to the best of my abilities.

Tests:

• PayKit Tests
• PayKitUI Tests

Changes:

Release 0.6.0