jshint: Add another global - 'exports'.
Auto-start testing when all requested agents are connected.
browserstack: Store original agent identifiers under 'farm' property.
browserstack: Fix error - stringify into the querystring not JSON string.
browserstack: Do not relaunch tunnelier, if it is already running.
options: Use empty array as default for config.browsers.
yeti: Rewrite launching logic to use promises.

Cleaner.
yeti: Pass normalized agent object in agentConnect/agentDisconnect.

Simply a name made it impossible to effectively mach agents for
equality.