FEATURE: Export multiple records (as BibTeX).

Closes #132.
FIX: Misleading UI for attachments uploading.

Fixes #134.
FIX: Record is reset on attachment upload.

Fixes #13.
FIX: BibTeX exports are too generic.
TEST: Failed import from ISI.
FIX: Failed import from ISI.
TEST: Other failed import from JabRef.

Unquoted attributes.
FIX: Other failed import from JabRef.

Unquoted attributes.
PROCESS: Fix a Travis regression.

See travis-ci/travis-ci#2220 for more details.
FIX: Other failed import from JabRef.

Multi-line attribute indented using tabulation(s).
REFACTORING: More readable tests.

Fields are searched by labels rather than by IDs.
TEST: Report the activity of a researcher, since a given year.
FIX: Render error encountered erratically in tests.
TEST: Report the activity of a researcher since a given year as a bibtex file
MERGE: feature #132 branch.

- Fixed the related test so that it waits for the download.
- Fixed the feature so that the filename does not contain spaces.
FIX: Indentation of BibTeX exports.
FIX: French localization for "issue number".

See https://github.com/benel/Tire-a-part/wiki/Numérotation-des-périodiques
MERGE: Features #68 and #132.

Conflicts:
	settings.json
	templates/activity_html.html
Test: Count activity of a researcher since a given year as a csv file called 'references_by_RESEARCHER_since_YEAR.csv
Change Capybara.default_wait_time default value 

Default = 2s
new value = 5s

The aim is to try solve a timeout issue with travis..