[compute] Add create_or_import_keypair request
[compute] Add list_keypairs request
[identity] support get_user

* implementation
* tests
* cassetes
Merge pull request #2 from devpopol/feature/get_user

[identity] support get_user
Merge pull request #1 from stefanymarie/feature/AVIATORAPI-10

Feature/aviatorapi 10
be able to use base_url

-updated test
-updated cassettes
Merge pull request #6 from devpopol/feature/get_user

be able to use base_url