Move Manila API-Reference in-tree

Manila's API reference [0] was being maintained in DocBooks [1] and WADL [2] formats. In Mitaka, the OpenStack API documentation team decided to adopt new standards for writing and maintaining API reference. As part of this effort, all projects will be required to move their API reference in-tree. [3]

Manila will follow Nova's style of documenting it's V1 (Supported) and V2 (Current) APIs. [4]

[0] http://developer.openstack.org/api-ref-share-v2.html (Source: https://github.com/openstack/api-site/tree/8da6b92/api-ref/src)
[1] https://github.com/openstack/api-site/blob/8da6b92/api-ref/src/docbkx/api-ref-share-v2.xml
[2] https://github.com/openstack/api-site/tree/8da6b92/api-ref/src/wadls/share-api/src/v2
[3] http://docs.openstack.org/contributor-guide/api-guides.html#how-to-document-api
[4] https://github.com/openstack/nova/tree/25ac5a27/api-ref/source