[develop 2.0] merge 1.x client with 2.0

[fehguy]

Currently the master branch for swagger-js supports 1.0, 1.1, 1.2 swagger spec versions. The develop_2.0 branch supports the 2.0 spec only. For a client like swagger-ui supporting all versions of swagger, the process is to include the swagger.js (from master, currently 2.0.47) and the new version of swagger client (named swagger-client.js), and determine which to use at runtime. That's pretty ghetto.

The old and new versions have different namespaces, and can live in a single file. Would like to both (a) have a better process to separate the code between versions, and (b) let the swagger-js client determine which version to use when it's invoked, taking the logic out of the caller.

In all cases, it makes sense to have a single swagger-js file containing both sets of logic.

[fehguy]

addressed in 5b60f2a