Fixed some of the failing test cases

http://hudson.rhq.lab.eng.bos.redhat.com:8080/hudson/job/katello-api/176/TestNG_Report/

Modifications to fix the following test cases that were failing:
1. Create Activation key with name more than 255 characters
2. ContentDefinitionTests : test_createContentDefLongName
3. KatelloDistributorTests : test_distributorDelete, test_distributorRemoveCustomInfo, test_distributorUpdateCustomInfo
4. Create provider with name more than 255 characters