Remove GMT time zones - they are the same as UTC

As stated in the original discussion [1], "GMT tracks UTC and this is not
expected to change".

Originally fixed in Quozl's patch [1] in relation to issue #2195.

[1]: http://lists.sugarlabs.org/archive/sugar-devel/2011-March/030497.html
Include all UTC time zones

Fixes the issue where places like Tonga have their time zones excluded. They
need the UTC+13 and +14 instead of -11 and -10, as they are on the the other
side of the international date line to the -11 and -10 time zones.

This fix is related to bug #2195 and is based of Quozl's patch [1].
TL;DR: "increase UTC timezone coverage for Kiribati and Tonga." [1]

[1]: http://lists.sugarlabs.org/archive/sugar-devel/2011-March/030497.html
Fix UTC time handeling, fixes #2195

Using the solution suggested by Sascha Silbe [1].  TL;DR "All of the
UTC+X UTC-X timezones could be translated into entries in
/usr/share/zoneinfo/Etc. For example, "UTC-5" would be converted to
TZ=:Etc/GMT+5"

Simmilar to Quozl's patch [2].  Quozl explains his patch as "translating
from ISO 8601 to POSIX.1 format, by reversing the sign"

[1]: http://lists.sugarlabs.org/archive/sugar-devel/2011-March/030532.html
[2]: http://lists.sugarlabs.org/archive/sugar-devel/2011-March/030497.html
Add configurable database for age/gender selection

OLPC AU has asked to use grade-level instead of age in its intro and
aboutme sections. This patch enables this change by introducing a new
configuration file, group-labels.defaults into sugar/data. The file is
used by the age picker to determine which icons to use and what labels
to use for the icons. Internally, it still stores age as a birthdate
timestamp in gsettings. Additonal methods are included for converting
between age and the configuration.

In this version of the patch, the configuration file is for grade
level. An age configuration file will be proposed for the upstream
patch, which will leave the user experience unchanged from the current
default for Sugar users.

A few other changes included in this patch: (1) a reset button is
provided for clearing the gender selection (required by law in some
places, including AU); (2) consolidation of the age and gender code
used by both the intro screens and aboutme cpsection; (3) provision
for reformating the age panel if screen rotation makes the panel too
wide to fit. (3) to meet another requirement for AU, the group label
setting is saved to gesttings in order to determine whether or not the
group label has ever been set. It has not been set, the age intro page
is shown boot.
Fix age/gender INTRO widgets visibility

Signed-off-by: Martin Abente Lahaye <tch@sugarlabs.org>
Fix age/gender flawed default-nick logic

Signed-off-by: Martin Abente Lahaye <tch@sugarlabs.org>
Fix age/gender INTRO gender-selection and CP grade setup

Signed-off-by: Martin Abente Lahaye <tch@sugarlabs.org>
Merge branch 'tchx84-configurable-groups'
Fix age/gender i18n

Since the labels for the age-selection widget are taken from an
environment variable (no longer hard-coded) they are not included in
the strings for i18n. This patch adds default values to agepicker.py
so that they are included in the Sugar POT file.
Fix age/gender flake8 issues

Signed-off-by: Martin Abente Lahaye <tch@sugarlabs.org>
View Help: don't use symlinks for images directory

We can't create syminks if the Help activity is installed
in /usr. Instead rewrite the url at the client side.
The symlink was used to not duplicate the images for every language.
Close dialogs along with activities - fixes #2503