Add support for async boot scripts
Merge pull request #50 from strongloop/feature/support-async-scripts

Add support async scripts
Bump version
Merge branch 'release/2.1.0' into production
Merge tag 'v2.1.0'

2.1.0
Fix conflict
Implement mixin loading

In accordance with the latest mixin cleanup in juggler.
Removed normalization (see: juggler)
Perform normalization
Minor fixes
bootSources => bootDirs
Fix remaining PR issues
Fix mixinDirs vs. mixinSources, minor touchups
Minor touchups after rebase
Fix conflict