Corrections on XML output, addition of XMP output

Right injection of builddate in TOOL_DATE, fixes issue #397
Generation of subjects, rights and creators
Use of CheckMessage to group the errors
Add a XMP output to give a standardized output
Extracts real identifier of epub
Modified the unit tests accordingly
Limit to 1g the memory for the tests
Merge pull request #421 from tledoux/issue-tooldate

Corrections on XML output, addition of XMP output