cylc.py: Fix user_name for rose bush and fix substring mismatching bug

Fixes:
 * potential rose bush bug when a user has deleted their ports file for a running suite which would result in it not being shown as running even if it was.
 * pgrep matching for suite names was inadequate (would now let through anything due to the exact matching). This retrieves all potential pgrep matches and checks them for exact matches for running that suite.

@matthewrmshin - please review.