Started migrating the tests from issue into workpackage #1754

Starting with the validations, we're moving everything out of issue into
workpackage: Accompanying this, the tests are migrated into specs. This
branch concentrates on moving the validations.

  * added shoulda for simplified testing of validations
  * added date_validator to simplify&fix date-validation
  * moved the basic-validations (presence_of, date-validations) into the workpackage_basics_spec.rb
Adding the more complex validations (re-/scheduling, versions etc.)

Also pulled up lots of methods from issue, that are now grouped in
various concerns under models/work_package: This is just a test to see
how much travis/ci likes this, for now it is only an organizational
means to work on the transition without interrupting the
work-package-core too much.
fixing specs: getting validations for workpackages in the workflow-specs to run
fixed specs for the planning-elements
Started migrating the tests from issue into workpackage #1754

Starting with the validations, we're moving everything out of issue into
workpackage: Accompanying this, the tests are migrated into specs. This
branch concentrates on moving the validations.

  * added shoulda for simplified testing of validations
  * added date_validator to simplify&fix date-validation
  * moved the basic-validations (presence_of, date-validations) into the workpackage_basics_spec.rb
Adding the more complex validations (re-/scheduling, versions etc.)

Also pulled up lots of methods from issue, that are now grouped in
various concerns under models/work_package: This is just a test to see
how much travis/ci likes this, for now it is only an organizational
means to work on the transition without interrupting the
work-package-core too much.
fixing specs: getting validations for workpackages in the workflow-specs to run
fixed specs for the planning-elements
pulled up changes to the scheduling-rules into the module.
rebased&merged changes
re-merged the changes from the unit-tests-branch&fixed the tests.
Merge pull request #384 from opf/feature/rails3_migrate_issue_validations