Bump version to 0.1.1
Update README
Bump version to 0.1.2
Support Trace and Message payloads

This supports logging of `trace` and `message` payloads. The `Rollbar`class has
been refactored into a client object, where you can invoke the different types
of payloads using either `Rollbar.trace` or `Rollbar.message`.
Merge branch 'support-different-payloads'

Conflicts:
	README.md
Bump version to 0.2.0