Ruby implementation of openEHR

We released version 1.0.2 to fix some bugs, reported from Simon McBride.
This notification suggested that more checks were necessary for release management. Thus, the openEHR ruby implementation project adopted "Travis-CI":http://travis-ci.org/ to check broader environments.
We fixed these errata.

• ItemStructure was not found in some conditions.
• IntervalEvent/Event calculate offset without timezone.
• Some minor bugs.

We experienced deep nested inheritance around openEHR specification/implementation could be hard to make out the point of bugs. (ex. AssumedLibraryTypes date/time, DvDateTime) Ruby version will challenge to refactor on Ruby way.