Wp 1045 services can register their constructor

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: http://jira.webinos.org/browse/WP-1045