Add pattern-matching arg to limit deploy hosts

Adds a flag to the deploy command --limit-hosts or -l that accepts a
pattern in one of the following formats:

• ~[regex] - if the pattern starts with ~ it is interpreted as a regular expression, this is not combined with any other option
• ![pattern] - can be combined with any other pattern to negate that pattern. May be combined with other pattern matching options.
• host[01:10] - range matching, works for ascii chars and numbers, including numbers with a leading 0, may be combined with other pattern-matching options.
• host* - Matches 0 or more characters in the set A-z, '_', '.', or '-'. May be combined with other pattern matching options.

This pattern is applied to the dsh_targets file to return a sub-set of
hosts to use as a deployment target.

Change-Id: I3ec5574c987ac576acc6cf23958542480a63ae66