moved all shading and tinting of color variables into _variables.scss

Now have variables w/ names like
$primary, $primary_dark, $primary_light,
etc.

Also counted occurrences of each and
recorded as comments in _variables.scss
updated comment
Merge branch 'master' into 464-refactor-color-variables
removed a lot of cassettes. tests were failing non-deterministically, this is a debugging attempt
color variable consolidation

renamed secondaries "accents", split up the
two shades of complementA into separate
variables.

Still working on the shades of $primary.
Started by create $primary_bg, $primay_text,
and $primary_border variables to help me
figure out how its being used where.
restored some color variation that was flattened out by the previous commit
moved button colors into named variables
moved checkbox colors into variables
pulled out color variables for sidebar filter buttons
more named colors in sidebar
pulled btn-utility colors out into variables
pulled search highlight color out into variable
renamed btn-whatever variables to button-whatever
moved pagination colors into variables
pulled highlights, alert colors, and main header colors into variables
pulling border and background colors into variables.
main h1 color moved to variable
fixed select for pagination "next" bg on hover
variables for pagination next hover color
variable for utility button hover colors