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