Fixes failing test

- this test was failing (on node 0.10.3 and 0.10.12) due to the expected
map not containing some of the proper mapping keys.
Failing test for sourcesContent
Spelling correction "Chunks" -> "Chunks"
Passing implementation of sourcesContent
Updates the readme with sourcesContent docs
readme typos
Merge pull request #3 from davemo/sources-content-support

Adds optional `sourcesContent` Support