Doc:  Remove old versions for consistent behavior

If you have older versions of the gem also installed, this causes the
"v2" functionality to be flakey.  (From IRC with Matt Ray, tested by
me)  

Included warning and command examples to show how to check and remedy 
this situtation.
Merge pull request #29 from behemphi/master

Update doc for mulitiple knife-rackspace gem version issue and fix.
KNIFE-314 fixed first gen server provisioning
Merge pull request #52 from rackerlabs/KNIFE-314

KNIFE-314 fixed first gen server provisioning
disable endpoints
bump fog version
fix rackspace_auth_url and remove rackspace_endpoint for KNIFE-315
update CHANGELOG with KNIFE-314
KNIFE-315 merge
Allow option to pass disk_confg to fog for new server creation

Also take care of some whitespace and cleanup tags while I'm in
Fixup missing comma so this will actually work
documented the --rackspace-disk-config option
update changelog
KNIFE-180 merge
KNIFE-312 rebase with master
KNIFE-312 removing rackspace_compute_url as users should be using rackspace_region instead