Added purpose attribute to generic messenger
Added purpose parameter to mq::message::epp

Has enum type which only has sample at the moment
Modified type name to make it clearer
Removed step_start
Merge pull request #202 from jbeast/add_purpose_to_mq

Add purpose to mq
Preparation for Release 0.55
Restored authorship of Perl modules copied from WTSI::NPG::Genotyping
Merge pull request #204 from keithj/devel

Restored authorship of Perl modules copied from WTSI::NPG::Genotyping