Only build the master branch on Travis
Handle feed burner xhtml atom feeds
Add specs for Preprocessor

Also, remove redundant outer loop specs.
Make RBX work on Travis

Also, remove the rbx group of gems - no longer needed.
Bump loofah gem to 2.0.0
Bump version for 1.3.0
Update CHANGELOG for 1.3.0

[skip ci]
Fix issue that causes duplicate content in preprocessed ATOM feeds
Allow multiple div tags, should they occur.
Bump version for 1.3.1
Update CHANGELOG for 1.3.1
Test both nokogiri and ox sax-machine handlers
Relax sax-machine dependency to allow 1.0.0
Update to sax-machine 1.0

[closes #234]
Loosen dependency requirements
Upgrade to Rspec 3.0
Remove invalid xml for itunes
Moved lstrip before preprocess.

Leading whitespace causes parse errors. If preprocess is called on a feed that has leading whitespace it can result in a missing parsed feed.
Bump version for 1.4.0
Update CHANGELOG for 1.4.0