CLI client refinements; location based time

For the Weather Skill:

When talking about the current city, the city name is generally not spoken (more natural)
A "pretty" name of just the city is used instead of the complete name
Works around the recurring issue with OWM where they report bad min/max temps (same as the current temp)
Changed "Location is not valid" to "I don't know that location" (people don't say "not valid")
For the Time Skill:

The timezone is extracted from the device location setting
Time responses are more varied and shorter
This change adds MycroftSkill.location_pretty and MycroftSkill.location_timezone properties.
PR: #492

Cli improvements:

"Input:" doesn't get intermingled with the output (usually -- long pauses can still cause it to happen)
"Output:" is now displayed
Ctrl+C is handled gracefully
PR: #494