Silent shifting

--quiet should work on all calls to log.info ("Looking for nearest .shifter.json, woohoo, etc")
--silent should also call 'quiet'
remove call to log.quiet()

silent() already calls quiet()
Merge pull request #113 from earnubs/patch-1

Silent shifting
Lock the watch at 0.8.0, since 0.9.0 is not working for recursive watching.
making sure that execution of scripts defined in build.json->exec are calling back into the main execution path
bumping version after PR #117
updating docs
Use mod.buildDir instead of hardcoded "build/" when generating coverage files.
Fixed corresponding tests.
These warnings serve no purpose in my opinion.
If I chose not to lint in a config or command line options, I don't need hundreds of messages telling me so.
less console
bumping versions and docs for 0.4.5 for PR #119
Added callbacks on error handling. Removed the log.error call on the compressor callback to continue processing.
Added callback handling on log.error() calls. Added unit tests and documentation
Code improvements. Added 2 more tests for bad uglifyJS builds on command line and rollups. Improved the documentation.
Fixed the failed test.
Ensure all fatal errors callback and make all callbacks flow back to the initial call to shifter.init() or shifter.add().

In init/add either call back if there's a supplied callback or process.exit(1) (in the case of an error) if there is no callback.
Merge branch 'bugfix-watch' of https://github.com/bmustiata/shifter
bumping version 0.4.6 for PR #116
Improvements as per pull request feedback.