customizer: minor cleanup of IE8 error messaging code

BS3 commits: 8bb1a3fc754eeda62c3ccdcd4da7c82854220a20
Variables for large and small input border radiuses

BS3 commits: 0d8f5fffa5a9a287140946b57570a036b9d33b99
Properly hide checkbox and radio inputs in button groups

BS3 commits:285feb4dd7cefbce0531d16db7bec8b99754f5d8
clean whitespace

BS3 commits: f6264b444a1d14089a59fc4d643489bc56da9966
ARIA support for collapse

BS3 commits: fb1ca10b99edc0f92eddd68b840f021da942afe9
grunt. grunt. run `grunt`. grunt and missing new line

BS3 commits: 48a1308e5dcf3fac575b74174ef07731203e335e,
c9602c29c337c912dab9dbbcadf0954a54026681,
9702579aeb3f0aeb677631782c2920d6cd804475,
9b9e2f5d139e0accd141d5b4b04bb332ed341e4f
Fixes 14319: Prevent jumbotron reflow by ensuring padding of .container isn't interferred with by .jumbotron side padding. grunt. grunt. run `grunt`. grunt and missing new line

BS3 commits: f2783fbf83fc063f85dd89af2d315ae290f7f38b,
6cec0399d0580f54cea5043a32ba7bb0868ac235,
c9602c29c337c912dab9dbbcadf0954a54026681,
9702579aeb3f0aeb677631782c2920d6cd804475,
9b9e2f5d139e0accd141d5b4b04bb332ed341e4f
grunt. Fixes 14319: Prevent jumbotron reflow by ensuring padding of .container isn't interferred with by .jumbotron side padding. grunt. grunt. run `grunt`. grunt and missing new line

BS3 commits: 48a1308e5dcf3fac575b74174ef07731203e335e,
f2783fbf83fc063f85dd89af2d315ae290f7f38b,
6cec0399d0580f54cea5043a32ba7bb0868ac235,
c9602c29c337c912dab9dbbcadf0954a54026681,
9702579aeb3f0aeb677631782c2920d6cd804475,
9b9e2f5d139e0accd141d5b4b04bb332ed341e4f
Fixes 14319: Prevent jumbotron reflow by ensuring padding of .container isn't interferred with by .jumbotron side padding. Fixes 14557: .form-group margin in .navbar-form. grunt

BS3 commits: f2783fbf83fc063f85dd89af2d315ae290f7f38b,
994d0b20aa19d673744f303ad81c1347a26b0c96,
6cec0399d0580f54cea5043a32ba7bb0868ac235