Fixes #589 - removes IE10 (x) default clear button

Fixes #589 - removes IE10 (x) default clear button.
IE10 adds an (x) to input fields to clear their contents. Since some
fields have a custom (x) added through the .clearable class, this
removes the default (x) on those fields.
Merge pull request #613 from codeforamerica/589-ie-input

Fixes #589 - removes IE10 (x) default clear button
Fixes #468 - top-aligns superscript text.

Fixes #468 - top-aligns superscript text. Superscripted text was
aligned to the bottom of the surrounding text, this commit top aligns
it instead.
Merge pull request #614 from codeforamerica/468-top-align-superscript

Fixes #468 - top-aligns superscript text.
Removes small redundancy

The `_mapCanvas` variable was defined in the global space, and was
queried twice. This commit removes the redundancy.
Merge pull request #615 from codeforamerica/detail-map-refactor

Removes small redundancy
Adds sass partial documentation

Adds documentation to imports of sass partials, so each sass file
doesn’t need to be opened to see what it’s for.
Merge pull request #618 from codeforamerica/sass-docs

Adds sass partial documentation
Cleans up JS

Adds some JS cleanup according to JSHint. Removes unused method, long
line length, mixed quotes, redundant variable declaration, and missing
semicolon.
Merge pull request #619 from codeforamerica/jshint-cleanup

Cleans up JS
Embed environment variables outside of assets

Moves environment variables that are accessed via asset ERB file to
instead be embedded in the webpage and retrieved at runtime.