`Entity.path` now uses the keywords `base` and `self`.

By default, the keywords `this` and `all` were used, now
it's modified and now uses `self` and `base` respectively.

The idea being `which='base'` returns the base path and
`which='self'` returns the path with the `id` of the entity,
while generating paths.

Fixing few more instances
Merge pull request #1470 from kbidarkar/base-paths

`Entity.path` now uses the keywords `base` and `self`.