Remove skip decorator from keypairs tests

This removes skips from:
    - test_get_keypair_detail (bug 980688 which is invalid and currently
works fine)
    - test_keypair_delete_nonexistant_key (bug 1086980)

Also removes an unused import.

Depends on change: I7e822c0661c563db01040ae2d57aacfe677d72b0

Change-Id: Id536c484753e219588b030d4fef9753f0e421b35
Merge "Remove skip decorator from keypairs tests"