Contributor checklist

• My changes are rebased on the latest master branch
• My contribution is fully baked and is ready to be merged as is
• I have tested my contribution on these platforms:
  • Ubuntu 15.10, Chrome 49.0.2623.110
  • Ubuntu 15.10, Firefox 45.0
• My commits are in nice logical chunks
• I followed the best practices when writing my commit messages
• I have made the choice whether I want the Bithub reward or not by omitting or adding the word FREEBIE in my commit message

Description

Dis been iterated at the Android repo

Issue template

• more explanations and tips
• clarify how to fill checkboxes (oops: Fail on grunt build #716, Message Notification Lag #726, Common emoticons should be translated to the relevant emoji #728, Sync per-conversation mute settings between mobile and desktop #729)
• actual and expected results
• remove link to the unofficial community forum (Moxie didn't want it in the Android repo's template, so I assume Desktop is the same)

PR template

• clarify how to fill checkboxes
• more about tests
• add link to an explanation for BitHub rewards (this has caused confusion before)
• explain that failing Travis CI build checks are normal
• other small stuff