Split requirements out to prod and dev.

Updated the fabfile to reflect that requirements.txt is now
requirements/prod.txt.

Refs #12273
Merge branch 'enhancement/12273' of git.osuosl.org:ganeti/ganeti_webmgr into enhancement/12273

Conflicts:
	requirements/prod.txt

Since django-object-permissions is now at 1.4.5, requirements.txt should
reflect this.