Adding support for regex based feed references.

For supporting regular expression based dynamic feed references,
enhanced answering adapter search to match regular expression instead
of direct key/values search in collectionAdapterMap.
Adding support for an option field "enableRegexFeeds" in WorkspaceConfiguration.

Adding support for an option field "enableRegexFeeds" in
WorkspaceConfiguration. This is to avoid less efficient looping in
WorkspaceHandler for searching an answering adapter from a map.
Change default value for enableRegexFeeds to false.

Changed workspace schema definition to mark defaul value of
enableRegexFeeds as false.
Merge pull request #236 from omanand/master

Regular Expression support for feed resource