When updating meta cache for a group of items, make sure empty values are cached

When updating the meta cache for, say, a group of activity items, it's possible
that some activity items won't have any metadata associated with them. In these
cases, we follow WP's update_meta_cache() by caching an empty array for that
item, so as to avoid cache misses.

git-svn-id: https://buddypress.svn.wordpress.org/trunk@8011 cdf35c40-ae34-48e0-9cc9-0c9da1808c22
Use correct date() format throughout unit tests

Also fix incorrect value reference in xprofile/activity tests. Props DJPaul

git-svn-id: https://buddypress.svn.wordpress.org/trunk@8012 cdf35c40-ae34-48e0-9cc9-0c9da1808c22
Reconfigure markup for radio buttons on group admin meta boxes

<label> elements should be applied to the individual radio buttons rather
than the entire set, for better accessibility and standards compliance.

The old top-level label is replaced by a fieldset and legend.

Fixes #5437

Props tw2113

git-svn-id: https://buddypress.svn.wordpress.org/trunk@8013 cdf35c40-ae34-48e0-9cc9-0c9da1808c22
POT, generated from r8013

git-svn-id: https://buddypress.svn.wordpress.org/trunk@8014 cdf35c40-ae34-48e0-9cc9-0c9da1808c22
Unit Tests: make travis-ci run with WP_DEBUG = true

git-svn-id: https://buddypress.svn.wordpress.org/trunk@8015 cdf35c40-ae34-48e0-9cc9-0c9da1808c22
Fix broken variable references in xprofile/activity tests

git-svn-id: https://buddypress.svn.wordpress.org/trunk@8016 cdf35c40-ae34-48e0-9cc9-0c9da1808c22
Unit Tests: switch to using `develop.svn.wordpress.org` for the travis-ci test environment instead of `unit-tests.svn.wordpress.org`.

`unit-tests.svn` is a deprecated repo and `develop.svn`'s test suite has diverged from it to the point where there are a couple of important differences in the test environment that affect how BuddyPress unit tests are run on travis-ci; the defaults for `error_reporting` and handling of functions that have been marked as deprecated.

Recent commits such as r8015 have been successful in adjusting the `error_reporting` level but our tests that have been marked as `@expectedDeprecated` are currently not handled correctly on travis-ci and on any local testing environments that use `unit-tests.svn` along with a development `error_reporting` level.

A consequence of switching the travis-ci script to `develop.svn` is that, as the WP core-to-develop SVN restructing happened between WP 3.6 and 3.7, SVN versions of WordPress prior to 3.7 don't have the seperate `src` and `tests` folders which the updated travis-ci script relies on. The tradeoff is that we'll have increased confidence in our travis-ci environment going forwards.

git-svn-id: https://buddypress.svn.wordpress.org/trunk@8017 cdf35c40-ae34-48e0-9cc9-0c9da1808c22