Added support for creation of WellsGroup objects from new parser Well and Group objects
Fixed copyright section
Create WellsGroupInterface from opm-parser Well/Group objects
Extracted common functionality from the three create functions
Changed the WellCollection addChild functions to be more specific, and strict
Added an else to avoid unnecessary checking.
Added building of WellsCollection group structure from new opm-parser objects
Removed the previously introduced getAndUnRootChild method
Merge pull request #493 from flikka/wellsmanager-group-refactor

Adding support for creation of groups from "new style" Wells and Groups (new parser)