Clear bundle stats for file paths

Bug in how it was clearing out the bundle stats.
Merge pull request #20 from Andrew-Hagedorn-ZocDoc/ClearBundleStats

Clear bundle stats
limit file system lookups on imported files.
optimize lookups on the file system when we are parsing imports in a file.
Merge pull request #21 from Andrew-Hagedorn-ZocDoc/speed-up-imports

Speed up imports
throw parseable mustache error
Merge pull request #22 from Andrew-Hagedorn-ZocDoc/throw-parseable-mustache-error

Cleaner mustache error
Merge remote-tracking branch 'origin/master' into CleanDirectoryInTestsUsingNodeToAvoidCrossPlatformIssues
move unit tests into a folder.