Add regex support to client filters

[anowell]

Support for regex filtering of events (e.g. events?filter=^hello$) exists here:

metadash/app/scripts/models/event.coffee

Line 131 in 3a1e9e8

_.any(toArray(param), (p) -> check.match(new RegExp(p)))

But it's not implemented for clients:

metadash/app/scripts/models/client.coffee

Line 107 in 3a1e9e8

_.intersection(toArray(param), subscriptions).length > 0