Create MD objects with explicitly provided identifiers

Unfortunately, the MD object creation API ignores the
explicitly provided identifiers which is why we have to
send yet another PUT request.
Added couple of params to allow more granular control during project creation
Ability to remove report definition from a report. Removing results methods since they are obviously not on the API any more. What hapenned with them?
Refactored clone method into the project class. Command is just a tiny wrapper
Basic metrics can be generated directly out of the fact or attribute
Added a purge_report method
Merge remote-tracking branch 'upstream/master' into user-management

Conflicts:
	lib/gooddata/commands/projects.rb