Move most code into core library
Create sub-project structure
Merge in Android/Core projects, gradle

Note: This commit doesn't build yet.
Get gradle build working
Remove jars (they are handled by maven now)
Further clean-up of build files, .travis.yml
Add gradlew wrapper to git
Refactored code to clean things up
Fix line endings (CRLF -> LF)
Cleaned up unit tests
Refactor library initialization logic
Refactor error reporting logic
Get unit tests passing again
Refactoring, commenting, fixing TODOs
Remove local.properties from git
Make sendQueuedEvents synchronized
Added commenting/Javadoc, other cleanup
Fix bug in initialization logic
Fix bug in FileEventStore
Refactor initialization to fix shutdown bug