Add specs for new parameter and updated documentation as well.

These counts significantly increase the load time for these
requests. Users can now opt in to receiving the counts by setting
`with_counts=true` in requests. This is a breaking change, but hopefully
a fairly minor one.

Updates specs to use new rails5 format.

The old format:
`get :show, { some: params }, { some: headers }`

The new format:
`get :show, params: { some: params }, headers: { some: headers }`

Removed all the unnecessary include of `WaitForAjax` and `ApiHelpers` in the specs.
Removed unnecessary usage of `api:true`

Signed-off-by: Rémy Coutable <remy@rymai.me>

Restore changes for api spec files

Fix error in rspec Users

Delete extra space Repositories-spec

Signed-off-by: Rémy Coutable <remy@rymai.me>

[e44da1c] Add Label API expected keys to tests

[ac929c8] Update Label API documentation