Wireless setup client

@aatchison and @jdorleans added a new client to set up wireless networks on the Holmes unit.
PR: #362

Speech Speed Setting

@forslund added configuration for the Mimic TTS engine to change speech speed.
#334

@ParkerMc made some changes to the ArchLinux build script.
PR: #359

Push to talk and bug fixes

@penrods added push to talk as well as some usability tweaks.
PR: #365

• Pressing the button when it isn't listening starts it listening
• Pressing the button when listening will stop the listen
• Added a mycroft.util.signal() mechanism for out-of-thread communication
• Pressing the button now creates an "buttonPress" signal from the Enclosure
• The viseme playback and aplay check for the 'buttonPress' signal to abort
• Removed "Sorry I didn't catch that", irritating during false activations