Clarify mapping labels

* Rename query params to parameters
* Add an abbreviation for TNA
Introduce a visited link colour

* Bootstrap comes with link and active link colours, but no visited
colour
* Set visited link colour to purple
* Create a colours file for this variable
Only apply visited colours to main content

* Stop links in the header, which are against black, from appearing
purple
* Wrap main role area in a 'content' class
Switch mapping filter to use a bootstrap form

* Use bootstrap's form-inline class and markup and remove custom filter
label and input styles
* Add placeholder text with example path
* Add a filter icon to input field using boostrap pattern, with tooltip
* Cleans up vertical alignment and attempts to clarify feature
Give new mapping button primary styles

* Switch from success style, we haven't succeeded yet
Don't apply visited link styles to buttons

* Create variables for each button's text colour, this isn't already
provided
* Use these colours to override the visited text colour
* eg Stops blue buttons having purple text
Connect filter bar with filter button

* Keep UI elements contiguous
Add margin helper classes

* Easily add and remove margins based on the baseLineHeight defined by
bootstrap (20px)
* Avoids the need to create CSS classes that simply manipulate margins
Apply scaffold font styles to labels

* Labels were being styled at 14px/20px, when all other text was
13px/18px
Remove the filter icon

* Icon is confusing
Match pagination and default button height

* Pagination when placed alongside a button looked awkward
* Create a structure import for structure based variables
* Update pagination to be 30px high (default button size)
* Add a default for border radius too
* Only apply bottom margin on pagination
Place no mappings messaging in filter form

* Move "no mappings" and "remove filter" messages to the Filter by path
label
* Make "remove filter" link available on all filtered results pages
Put pagination and new mapping alongside

* Avoid stacking controls
* Move (presumed) less used 'new mapping' button to the right, with
pagination on the left
* Bring new mapping button back to left when no pagination, or no
mappings
Limit pagination window to 2

* The default pagination window made the number of page links on screen
unruly, and at thinner page widths would break the layout.
* See https://github.com/amatsuda/kaminari
Reword new mapping button to add mapping

* Switch from new to add, but leave 'new' in place on create pages/forms
* Add a plus icon
* Move button to a partial
Add a mappings count header to index

* Show a total count for all mappings
* It helps illustrate how much a list has been filtered
Add bootstrap page header classes

* On sites and mappings indexes use the bootstrap page header class on
the H1
* This increases vertical spacing and adds a light horizontal rule
Remove "no mappings" message

* With a header containing the mappings count, this message in the
filter label is no longer necessary
Only use new transport for headings

* Keep body copy using bootstrap defaults
* Body copy now uses: "Helvetica Neue", Helvetica, Arial, sans-serif
* Improves button spacing and icon alignment in bootstrap
* Conforms with other admin tools