add eclipse pref for import order

- should be the same as in Android Studio
- rename packages to lowercase
move ProjectData to own File
Merge pull request #598 from Catrobat/issue#596

add eclipse pref for import order
refactor junitTest cleanup

when executing all junit tests, some tests did not cleanup
the test projects - they were left in Pocketcode folder.
a helper method is called in teardown() to delete these
projects after the testcase
Merge pull request #593 from Catrobat/cleanupJunitTests

refactor junitTest cleanup