Travis: remove PHPUnit exclude groups on php 5.2

There is a bug in the version of PHPUnit that runs on PHP 5.2, that
won’t run a group that is excluded.

See #143
Travis CI: change PHPUnit order

On PHP 5.2 we need to remove the exclude groups `ajax` and `uninstall`
from the XML config file because of a bug in the legacy version of
PHPUnit that runs on that PHP version. We need to run the general tests
for multisite before doing that, otherwise those groups, which are
normally excluded, will be run as well. We run those groups each on
their own after running the general tests.

See #143
Travis: get latest uninstall tester on PHP 5.2

We can’t use composer for dependencies on PHP 5.2, since it requires
5.3. Instead, we have to download the uninstall tester manually.
However, we had hardcoded the version number in the URL. Now we’re
using git to checkout the latest version. This doesn’t guarantee that
it will be the same version specified in composer.json, but at least we
won’t need to update it constantly.

See #143
Merge branch 'issue-143'
Use log meta functions instead of direct queries

Using direct queries means that the cache is not cleared, so when we do
it correctly later and use the API, we’ll get cached results that
aren’t correct.

This is in preparation for #213
Use points log meta API in logs regenerator

Fixes #213
Add function to delete all meta for a points log

This way the cache will be cleared properly.

Includes unit tests.

See #226
Clear cache when deleting all meta for points logs

We were previously running these queries directly, which means that now
that we’re using WordPress’s metadata API, there would be stale log
meta in the cache.

See #226
Fix points logs cleaning tests

These tests were checking that log meta was being deleted, but because
they were using `WordPoints_Points_Logs_Query`s they weren’t actually
testing whether the metadata had been deleted, because the query will
only work if the log still exists, and in this case, it doesn’t. What
we need to do is get the IDs of the logs and then retrieve all of their
metadata with the get meta function.

See #226
Tabs not spaces

See #226
Don't attempt to use a string as an array

For some reason that doesn’t work very well.

This was caught by the Scrutinizer, and brought to our attention that
our tests weren’t actually testing this portion of the code. Now
they’re fixed.

See #226
Better meta result checking in the tests

Rather than just checking for an empty result, which could also
indicate failure, we need to check for the expected result.

See #226
Merge branch 'issue-213'
Update l10n config