rev to a new version of the analyzer

Upgrade to the new version of the analyzer:

- this lets us remove some code that had been copied out of the analyzer source base (the code itself moved out of a library that had dart:io dependencies into one that didn't)
- capture a bug fix w/ analyzing files w/ external file references (fixes #706)
- added a keybinding to let us run the tests (if, say, the spark menu stopped working due to weird polymer css issues)

@bwilkerson @scheglov