FIX brainvision:  ELP point coordinates

 - fix variable name conflict
 - allow complete customization of point order in ELP files
TEST brain vision:  save Raw with buffer size smaller than file
FIX brainvision: event handling

 - only read events once
 - FIX create stim channel when buffer is not whole file
FIX:  remove unused parameter
ENH:  Option to fix psychtoolbox/stimtracker events

Option to fix events from a vmrk file from a recording where triggers were
sent by psychtoolbox and recorded through the stim tracker (KIT setup)
STY
OPT:  make KIT and brainvision readers to share read_elp

(move read_elp to mne.coreg)
TEST:  read_elp
FIX:  initial file offset when reading from brainvision eeg
API: add deprecated ch_names parameter for backwards compatibility
ENH:  remove KIT specific fix and add general interface to events
STY:  array shape in DOCs
ENH:  keep brainvision events coser to vmrk (duration instead of offset)
FIX:  add/remove stim channel on demand
FIX:  only synthesize stim channel if at least 1 event is present
FIX:  Exception for missing positions in elp
FIX:  py3
Travis test case without optional dependencies

* Patsy and statsmodels are now installed
* Pandas installed using pip rather than apt-get (need more recent
  version for statsmodels)
Cleanup + comments
Put apt-update after get-key