Refactored classes for Scratch representation

* renamed: ProjectCode -> RawProject
* changed: Project inherits from RawProject
fixed retry-functionality
extended and refactored web api

* added: Scratch web api for project infos
* changed: moved web request functionallity to common
* changed: renamings
extended resulting Catrobat xml header; extended project information

* changed: converted Catrobat xml header extended and refactored
* added: project information update by web api usage
* fixed: project superclass init
* added: version file
extended xml header test

* changed: Catrobat xml header test
* added: common functionality
* changed: Catrobat jar update: access to language version constant
disabling jar test until fix
cleaning pep8 warnings