fix(webhook): change regex again

Pattern update to be a little less ambiguous (`\w` -> `[aA-zZ]`)
refactor(webhook): remove pattern match

Remove pattern match to have the add-on look at all messages (these
regex variations never seem to match “something AA-11111” but will
match “AA-11111 something” and other variations).
Merge branch 'improve-regex' of github.com:deskfed/jira-link into improve-regex

Conflicts:
	atlassian-connect.json