Refactor sidebar configuration

Instead of editing an if statement (which could get ugly quickly), just
edit configuration arrays of conditional tags and page template checks.
Minor naming tweak
Clarity over cleverness
Refactor Roots_Sidebar
Fix callback reference
Merge pull request #556 from retlehs/sidebar_config

Sidebar config
Single template now has same tags output as archive
Add missing semicolons
Update .gitignore
Use PHP Alternative Syntax in header templates
Fix #561 - Use TOC.md for documentation TOC
Roots 6.1.0
Add grunt.js build script

- Move Bootstrap LESS files into new subdirectory

- Change app.css to app.less, add @import's to utilize
Bootstrap variables and mixins

- Remove plugins.js and main.js

- Move Bootstrap JS plugins into new subdirectory

- Add new _main.js file with example DOM-based routing
script that works off the WordPress body_class

- lib/scripts.php has been updated to remove all extra
CSS and JS files and also places JavaScript in the footer
Move Nav customizations into its own file

Considering the nav customization/cleanup code is fairly involved and
important, it shouldn't be hidden in the middle of cleanup.php
Allow the sidebar config functions to accepts args
Comment should be consistent
Return instead of echo class names
fix roots_fix_duplicate_subfolder_urls isset check

function checked if $matches[1] & $matches[2] were set, but next line operates on $matches[1][0] & $matches[2][0], so under certain circumstances, you get the following Notice: Undefined offset: 0.

Now it checks for the [0] offsets from the start.
Merge pull request #576 from jloosli/master

Fix bug on roots_fix_duplicate_subfolder_urls
Unset menu bugfix. Support for additional classes.

Previous nav walker resulted in an error when no menu is set.
This fix supports supplementary classes i.e. nav-header nav-header-blue. 
N.B. Bootstrap classes (nav-header, divider, divider-vertical) must be added first.