Shortcodes: Fix [googlemaps] shortcode reversal false positive.

`jetpack_googlemaps_embed_to_short_code()` is intended to only reverse URLs in
the format of `https://maps.google.com` or `https://google.com/maps/`, but it
is matching `google.com` any domain.

For example, the following tag will be reversed into a `[googlemaps]` shortcode
even though it should not be:

<iframe src="https://docs.google.com/spreadsheets/d/19FacgevvN-GGS8SOlbMRVKkWDYSMDQEBfRmkwqaA9z8/pubhtml?widget=true&amp;headers=false"></iframe>

The problem is that the code mistakeningly tests for a `false` return from
`preg_match()` instead of `0` or `false`. Unlike `strpos()`, `preg_match()`
returns `0` if the pattern is not matched, and `false` if there is an error.
Because of this, the condition evaluates to true, and the function
doesn't returns early.

This bug was introduced in 7d5c5a77b25474798554fba4e8f72c853f96b507.
Change LinkedIn sharing URL to secure URL

LinkedIn supports https throughout their site and users should be sent
to https links when possible. This commit changes the Share_LinkedIn
class to use https for the sharing link used in the process_request()
method.
Reverting some unintentional whitespace changes
Minileven: remove WP 3.4 backward compatibility

See #301
Likes: remove pre-3.8 styles

See #301
Likes: remove pre-mp6 filter

See #301
General: no need to add an mp6 class anymore
Likes: remove another mp6 filter
Omnisearch: remove pre-mp6 CSS
Contact Form: remove pre-mp6 CSS
Related Posts: add filters to customize post context

See #361
Merge pull request #981 from jeherve/update/old-version-compare

General: remove No longer necessary backwards compat code
Contact Form: add required and aria-required attributes

Fixes #459
Using $this->http() to make http usage consistent

Switching from a hard coded https in the LinkedIn class to using
the http() method to make the prefix usage consistent across the
methods and classes.
Updating PHPUnit annotations in unit tests

I've been omitting and misstating some of the annotations on the
unit tests I've been committing, and this commit should fix those
annotations.
Merge pull request #985 from enkrates/update-since-tag-for-tests

Updating PHPUnit annotations in unit tests
Shortcodes: add shortcode param to all shortcode_atts calls

See http://wp.me/p56-127
Fixes #527
Add `absolutize_css_urls` function and unit test.
Err, make `absolutize_css_urls` static. Oops.
Merge pull request #984 from jeherve/add/grunion-required-attributes

Contact Form: add required and aria-required attributes