New 'emotion' (motors...) tests with pytest + a bunch of fixes

A lot of changes to have pytests instead of old unittests for 'emotion' code.

Apart from the new tests, most significant changes:

• pseudo axes set_position is now only changed once when pseudo axis is moved, or if real axis is moved; should solve issue reported by Tiago (see !210 (comment 4405))
• pseudo axes positions were not always set right at the end of real motors motion: an extra call to '_calc_from_real()' has been added when real motors state goes back to READY
• CalcController.set_position() method was reporting wrong values if axis had an offset (calculated with previous offset)
• a race condition with motor being reported as READY too early in state callback has been fixed
• jog reset: at the end of jog, positions were reset but it was not done synchronously, now it's fixed
• Axis.apply_config() do not reload the configuration by default
• emotion plugin has been refactored a little bit, to make it more readable