This changeset adds support of max_instances and available_instances.  Resource manager tracks all registered instances, except those in the DELETED state.  Its could_reserve? and numbers reserverable methods responds positively when the total number of undeleted instances fall under the max_instances limit.
Recognize db2 and informix as valid databases for generation of valid DATABASE_URL
Test case for detecting db2 and informix as valid RAILS databases and converting urischeme to ibmdb
Test case for detecting db2 and informix as valid RAILS databases and converting urischeme to ibmdb
Improved the clarity of health check failure messages.

[#63057646]
Merge pull request #111 from praveend/master

Add db2 and informix as VALID Rails relational database types
Merge pull request #85 from jackfengibm/max_instances

This changeset adds support of max_instances and available_instances.
Auto-merge remote-tracking branch 'upstream/master'