Stop hardcoding grid breakpoints in responsive alignment utility classes

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v4 - Remove unused sass_repo variable

Per https://github.com/twbs/bootstrap/pull/17997#discussion_r42564175 ; thanks @vsn4ik !
Refs #17769
/fyi @croaky

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v4 - Update grunt-jscs to 2.1.0 to use JSCS 2.x

Fix three small typos

Add #17913 to Wall of Browser Bugs

Refs https://code.google.com/p/chromium/issues/detail?id=544290
Refs https://bugs.webkit.org/show_bug.cgi?id=150271
Closes #17913
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Fix typo in docs for tooltips.

Remove redundant `<span class="sr-only">...</span>` for close buttons

Since `aria-label` is used, it's not necessary anymore.

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/fyi @mdo

Reset iOS rounded inputs

Remove double bottom border on sub header in dashboard example

Tweak .text-capitalize example to show what happens to interior capital letters

Make $card-border-radius default to $border-radius

Use .blockquote class in V4 examples page

Add Wall of Browser Bugs entry for #14975

See https://bugs.webkit.org/show_bug.cgi?id=150079
Closes #14975
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They already share the same value (`.25rem`)
Refs #17597
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Remove #9774's entry from Wall of Browser Bugs

See http://trac.webkit.org/changeset/190893
Refs #9774, #14907
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Fix #17888

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Avoids cycling carousels when the page isn't visible.
Closes #17710
Refs #15566

Add Wall of Browser Bugs entry for Safari related to #17438 / #14237