SCADefinitionsProvider changes

[Venkata Krishnan <fo...@gmail.com>]

Hi,

Under r638020 I have committed changes to introduce a SCADefinitionsProvider
mechanism for Tuscany modules to contribute SCADefinitions.

This was earlier being done following the convention of placing the
definitions.xml file in the META-INF/services directory.  Now this has
changed into a programming model where tuscany modules that contribute
intents, policysets, binding types, imple types, will implement a
SCADefintionsProvider and register it in the meta-inf/services directory.

Right now the tuscany modules that contribute to SCADefinitions such as
policy-security, policy-logging, policy-transaction implement the providers
as a reader of a definitions.xml file.  Its not that this is the only
option.  Modules can choose their own means of providing a SCADefinitions to
the runtime.

Thanks

- Venkat