SQL Capabilities Swagger (#1015)

* Initial Microsoft.Sql Capabilities swagger commit

* Minor description changes, add capabilities to compositeSql.json

* Update typo in swagger spec

* Add reference to capabilities API in
 sql.core.json

* Updated description in capabilities.json

* Removed 'Azure SQL' where appropriate, removed modelAsString

* Updated documentation, fixed status enum, removed unused definitions

* Consolidate enums, respond to PR comments

* Update descriptions

* Move description to appropriate spot

* Updated capabilities example

* Change Resource definition back to match Resource definition in 2015-05-01

* Change Resource definition back to match Resource definition in 2015-05-01

* Updated descriptions and operation id