Add try/catch for all data import processes

See merge request !186

Use the `exception` log method for better exception logging. This change the log
level to 'ERROR'

Adding tests for filters

Closes #186

See merge request !191

Fixing a typo

Closes #186

See merge request !190

Resolve "Add a query filter to sort meps by active constituency"

Closes #186

See merge request !189

Create the active_constituency

Closes #186

See merge request !188

Oopsie …

Closes #184

See merge request !187

FIX #184: Add a active_mandates= filter on queries

Closes #184

See merge request !185

All import processes now use a general try-catch during the import of each data
item. This ensures that even in the event of an error (due to a malformed data
piece for example), the import process will continue.

Errors caught this way are logged at the debug level.

Change git URL and cloning text/repository name after project rename

As someone highlighted it on the IRC channel, repository and issue URLs were not updated after past repository and group renaming, as it resulted in broken URLs (404, it doesn't seem like Gitlab handle any form of redirect)

This commit change part of the doc as well to reflect the change.

However, grep did match other parts: 

`clement@mbp:~/repositories/memopol$ grep -irnI political_memory .
./.travis.yml:36:    repo: political-memory/political_memory
./docs/deploy-openshift.rst:15:    Cloning into 'political_memory'...
./docs/deploy-openshift.rst:23:    $ cd political_memory/
./docs/development.rst:23:    $ cd political_memory
./docs/development.rst:59:    Cloning into 'political_memory'...
./docs/development.rst:67:    $ cd political_memory/
./docs/development.rst:81:    Obtaining file:///tmp/political_memory
./docs/hacker.rst:19:    $ cd political_memory/
./setup.py:12:    url='http://github.com/political-memory/political_memory/',
./src/memopol/templates/home.html:129:        <a class="btn btn-default" target="_blank" href="https://git.laquadrature.net/political-memory/political_memory">
./src/memopol/templates/home.html:133:        <a class="btn btn-default" target="_blank" href="https://git.laquadrature.net/political-memory/political_memory/issues/new">`

Should Travis stay there if nothing remains on Github?

I didn't touched matches for the pip package. Should it be updated as well? (`development.rst:81` and `setup.py`). Is the pip package to be renamed too?

See merge request !183

Update README.md

Closes #182

See merge request !182

Updating the gitlab-ci.yml stuff

Closes #181

See merge request !181

Adding banners to the homepage.

Closes #169

See merge request !176

Fixing the version number for Django rest Framework

Closes #176

See merge request !180