"Message magic" regexps are too greedy

[apparentlymart]

We currently match the special "deploy to" messages using regexps that capture the environment name using \S+.

This is too greedy because it prevents writing messages like Deploy #12 to foo: baz. In that case, the environment name is parsed as "foo:".

Instead we should make this more restrictive with something like [\w\.\-]+. That allows environment names to either be identifier-ish strings or hostnames.