pillar: specify explicit exception type in `except` clause

************* Module salt.pillar
W0702:334,20:Pillar.render_pillar: No exception type(s) specified
Fix pylint compatibility in travis

See https://github.com/saltstack/salt/pull/6304#issuecomment-21590082
Minor formatting fixes.
Fix #6326: bridge.show returns none when no bridge is found
Fix some formatting (line length)
Sort 'comps' and 'line' when comparing Debian repos, Fix #5517
Only sort everything after the URL in the line
Don't sort the repo title
No general exception catching while rendering pillar. Refs #6305. Refs #5910.

* All errors while processing pillar data are now logged besides being returned.
* Removed the general exception catch. All we need to is check for the expected data type. If it ain't, log the error and continue to the next iteration.
* Added a mocked test case which besides testing the issue reported on #5910, also tests for the proper includes data format and if salt fails accordingly and even if common data is merged.
Make state.show_{highstate,lowstate,sls} work with PyDSL

PyDSL needs an active HighState. If you have any sls file that uses the "pydsl" renderer you cannot use state.show_highstate, state.show_lowstate and state.show_sls at the moment.
Pushing the HighState on the active queue fixes this.
Document how top files are compiled from different envs
Add a 4th step to the states tutorial

This adds a step showing how file roots can be used to "promote" states
from dev -> QA -> prod.
Add practical example
Add link to step 4 of walkthrough to main docs index page
Escape the $s because they're being interpolated
bsd_shadow: add note on escaping dollar signs
Use proper escapes for Travis' sanity