Remove Travis build status.
Release notes for 0.5.0.
Merge pull request #43 from sjrd/0.5.0-release-notes

0.5.0 release notes
Update documentation to reflect (anticipated) v0.5.0
Add page about usage of SBT plugin

Also fixes #37: Document how to cross build
Improve documentation structure
Add links to CLI distribution
Add links to API docs
Fix #25: Add tutorial to quick start new devs
Add big "latest release" message on front page