Multiple fixes: code styles + properties to Array + fix rendering context for breadcrumbs

- Convert properties to Array and apply code styles
  - There are some properties like classNames, attributesBindings and
classNameBindings that should be Arrays. This commit converts them to
Array.
  - This project does not have code style guide, however I noticed a lot of
double quotes mixed with single quotes. This commit converts some
double quotes to single quotes. It will make the life easier for
contributors.

- Fix context rendering for breadcrumb templates, fix issue when items are added or removed to a breadcrumb and add tests.
This commit fixes en issue reported in
https://groups.google.com/forum/?fromgroups=#!topic/ember-bootstrap/rEgT
g5q2M-8

  - Fixes rendering context for the templates used in breadcrumb
  - Adds regression tests to make sure this issue is not coming back
  - Fixes issue when item are added or removed from the breadcrumb content