Fix WebinosService inheritance.

Jira-issue: WP-1045
Add _webinos.registerServiceConstructor function

API service constructors should be registered with this function like:

_webinos.registerServiceConstructor('http://webinos.org/api/test', TestCtr);

This is more flexible compared to the old way of hard coded names for each
API. For compatibility, till all APIs are updated to use this function the
old typeMap with the hard coded names is still used by the discovery as
well.

Jira-issue: WP-1045
Fix undefined errors for typeMapCompatible

Build the compatible type map once these service constructor are available

Jira-issue: WP-1045
check for _webinos

for compatibility, don't fail if _webinos isn't defined.

Jira-issue: WP-1045
Merge pull request #6 from aldafu/WP-1045-services-can-register-their-constructor

Wp 1045 services can register their constructor