Fixes to montage

- Moved viz code to `viz/montage.py`
- Use `os.path.splitext` for determining file extensions
- Match montage on entire name to avoid ambiguity
fix path
lacks_* --> skip
fixed typo in doc
Fixed permissions
Skip missing sensors

When some sensors are defined in the montage file, but not present in
the info structure, they are silently skipped.
Throw exception when no sensors match

Also don't use try/catch
Added montages to setup
fixed mayavi check
fix mayavi import
Merge pull request #14 from wmvanvliet/montage-fix

Montage fix