Added server check to memcache related test
[fix] #4740 headers show when no record
Refactored data providers
Query fix in mod_articles_archive so it works in PostgreSQL. Fixes #3292
Modify JResponseJsonTest
Really fix it this time
Merge pull request #4749 from infograf768/usernotes

[fix] #4740 Users Notes: headers show when no record
Improvements to JSchemaChangesetTest
Merge branch 'staging' of github.com:joomla/joomla-cms into staging
Updating tests for JTable classes
Merge pull request #4758 from nibra/test-memcache

Cleanup of JCacheTest
Cleanup JVersionTest
Add note to CONTRIBUTING