Fix tab-completion of --flags under OS X

--flags were not tab-completing under OS X. This was due to the whitespace
collapsing regular expression using the '+' token (meaning one-or-more), which
isn't supported in OS X's version of sed.

Using the more portable '  *' instead of '[  ]+' fixes this.

Additional cleanups

* Remove unecessary embedding of tabs in the file (nova bash-complete doesn't
  emit tabs, so the regular expressions don't have to handle them)

* Restore logic to exclude -h from tab-completion (was lost in last
  tab-completion cleanup)

* Add similar exclude logic for -i

Fixes bug 1266667

Change-Id: I7e1fe8382d9b5295d0bbc1cde2b89550d5a4e21c
Merge "Fix tab-completion of --flags under OS X"