Validate required args exist for gear actions

Ensure a file is specified and that it exists for `gear prepare`.

Ensure a valid deployment id is specified for `gear distribute`.

Ensure a valid deployment id is specified for `gear activate`.

Bug 1070656
Merge pull request #4838 from ncdc/bug/1070656-require-args

Merged by openshift-bot
Merge pull request #4845 from danmcp/master

Merged by openshift-bot