[pymorse] print message if no concurrent.futures

Following the message from Brent Komer <brent.komer@gmail.com>
Fri, Oct 11, 2013 at 6:09 PM on morse-users@laas.fr for Python2.

- add requires=['futures'] in setup.py
  https://pypi.python.org/pypi/futures
- fix typo :-)
[ci] add more test {gps,pose,sick,vw}
[doc] Complete rewrite of the 'what is MORSE' page