improved simple wrapper class

added general definition of all resources (pool accounts, grid-mapfiles)
to the simple class as virtual resources
added list of enabled resources to the simple class
added realise_* clases to enable specific sets of virtual resources
improved group generation

moved group hash generation into separate ruby function
bug fixes and improvements to simple wrapper class

fixed creation and deletion of pool accounts and single account
fixed grid-mapfile / groupmapfile generation
Merge pull request #5 from rwf14f/master

implementation of 'simple' wrapper class in a working state