Fixed sizing bugs in flexible text field
Converted placeholder property from binding to computed
Added method string to keyDown event object
Refactor and cleanup of tags input

Move methods and event handling from child views into main tag input view. This helps when integrating tags input into other views.

Allow item template to be defined through parent container template property. Thus the item listing template can be specified by handlebars as follows:

`
{{#view Emberella.TagsInput width=200 delimiter=';,'}}
<strong class="emberella-tag-item-content"><i>{{view.content}}</i></strong>
{{/view}}
`
Broadened regexp support for tags input delimiter

Should be able to support an array of strings AND regular expressions in the 'delimiter' property.
Added delimiter test to addTag method

Also, addTags method retainFocus argument defaults to current focus state
Refactored delimiter CPs; Fixed tag capture on blur
Improved support for objects as tags

Also added handling for up and down arrow keys

Fixed a bug that would sometimes cause the tag input to lose focus after the addition of a new tag
Handle up/down arrows when focus on tag item
Added 'highlighter' property to tags input

Set 'highlighter' to an object where each key is a class that may be added to the tag item and each value is a function.

Each function in the object will be called in the context of the tag item view. The content of the item view will be passed as an argument.

If the function returns a truthy value, then the associated object key will be added as a class on the tag item's element.

Otherwise, no additional classes will be added.

Use this functionality to alter the appearance of tags that match certain criteria.