Re-write and clean up the code
Bump to 1.3-SNAPSHOT and recursive sources/externs

The version number in the pom has been updated to 1.3-SNAPSHOT to
reflect the breaking changes which have been made. The README was also
updated to reflect these changes.

Sources and externs will recursively include all javascript files
beneath them. The externsDirectory and sourceFile options have been
removed entirely.
Stop double-run of the ClosureCompiler on watch

Doesn't fix the double-run of the nodejs run task, though. That one's
harder.