[doc] Added/Updated jsdoc for Rackspace

I found that there was a lot of missing documentation for the Rackspace portion of the SDK, tried to JSDoc it, only to find out that it wasn't all there.  This update makes each service a module ( e.g. dns, compute, etc ) and adds in all the exported functions as @functions.  There were also a lot of things using jsdoc notation that weren't being read properly.  Additionally, there were some grammatical changes made in a few places to standardize without changing the meaning of the previous documentation.

This provides a decent segregation of functions by service type.  I still need to add in everything that is pulled in from the base OpenStack, but would like some feedback on this before going too far.  I didn't see anything about jsdoc requirements in the contribution guidelines.  I checked out a few of the other providers, but I didn't see any sort of standard here.

A working example can be seen here - http://pkgcloud-rs.sheppyreno.com/rax2/module-databases.html

This was created by running `jsdoc -r .` from the lib/providers/rackspace folder using the default jsdoc .conf file.

I believe that to get Openstack to properly be pulled in, I will have to change the @modules from '@module service' to '@module provider/service' then use a @borrows where appropriate.