Gets detailed information about specified user-id

According to Identity API Specification [1], user can get details about herself with following request:

GET v2.0/users/<USER_ID>

This was not supported by SoftLayer driver, we are supporting this using SoftLayer_Account service's getCurrentUser [2] method.

[1] http://api.openstack.org/api-ref-identity.html#identity-v2
[2] http://sldn.softlayer.com/reference/services/SoftLayer_Account/getCurrentUser
Retrieved specified user details.

Corrected getCurrentUser with getUsers with specified user id.
Merge branch 'user-get-request' of https://github.com/anil-kumbhar/jumpgate into user-get-request
If user doesn't exists corresponding HTTP code/message has been given
If user is unauthorized corresponding HTTP code/message has been given
Corrected pep8 error from previous build
User can display details of itself and its child only
Corrected pep8 error from previous build
Merge branch 'user-get-request' of https://github.com/anil-kumbhar/jumpgate into user-get-request
Always raised 404, even if user is unauthorized

User can retrieve details of all users that he has access to otherwise 404 HTTP error will be returned.
Merge branch 'user-get-request' of https://github.com/anil-kumbhar/jumpgate into user-get-request
Handled appropriate exception and raised others

Apart from exception handling user details are given if present.
Merge pull request #60 from anil-kumbhar/user-get-request

Gets detailed information about specified user-id