Added the ability to set the name of the header used for authentication to support ChilliProject (and any other ticketing system) that may use Redmine but authenticate with a different header.
Adding lastCallFailed method to AbstractApi to tell whether or not the last API call failed.
Created namespaced SimpleXMLElement to resolve an issue with addChild where it would not escape text properly (see http://stackoverflow.com/questions/552957/rationale-behind-simplexmlelements-handling-of-text-values-in-addchild-and-adda)
Merge pull request #58 from nerdo/master

Added the ability to set the name of the header used for authentication ...