added xmlpath dependency
added tests around PayloadXmlDecoder for issue #310
added documentation for PayloadXmlDecoder
Merge branch 'features/amqp-single-decoder' into features/no-encoding-header
Merge branch 'dev' into features/no-encoding-header
Remove message encoding header from Heka protocol.
Merge branch 'dev' into features/310-xmlpath
Merge pull request #430 from mozilla-services/features/310-xmlpath

adds a PayloadXmlDecoder
Merge pull request #434 from mozilla-services/features/no-encoding-header

Features/no encoding header
Add comment to clarify use of `a = b[n:n]` pattern.
Merge branch 'dev' into features/issue_423