Issue 279: refactor main view to use less memory
- no search term:  from 22MB to 0.9MB
- string search: from 22MB to 14MB
- entity search: from 22MB to 14MB
- strings & entity: from 22MB to 18MB

Also refactored some of the glossary view to use MVC
Merge pull request #282 from pascalchevrel/issue-279-fix-main-view-memory-consumption

Issue 279: refactor main view to use less memory
Issue #285: log performances of script
* logs normal views and json API perfs
* logging works only in DEBUG mode and with the PERF_CHECK constant set to True
Merge pull request #286 from pascalchevrel/issue-285-log-script-perfs-in-dev-mode

Issue #285: log performances of script in views and json API in dev mode
Issue #208 - On the fly TMX
Merge pull request #255 from TheoChevalier/issue-208-TMX-onthefly

Issue #208 - On the fly TMX
Get the strings for mozilla.org in TMX files
Merge pull request #287 from TheoChevalier/tmx-mozilllaorg-fix

Get the strings for mozilla.org in TMX files
Remove {ok} tags from mozilla_org strings
Merge pull request #288 from TheoChevalier/tmx-mozilllaorg-fix

Remove {ok} tags from mozilla_org strings
Refactor new tmx downloads view:
- consume a bit less memory in general (ex: 27MB instead of 29MB when selecting all repos for French, 14.5MB instead of 22MB when selecting only mozilla-central for Persian)
- don't put empty strings in tmx output
- use tabs instead of spaces in generated tmx (saves up to 2MB memory in file size and 0.5MB in memory consumption)
Merge pull request #289 from pascalchevrel/nobug-refactor-tmx-download-model-for-memory-savings

Refactor new tmx downloads view:
Issue #283: log bad API calls to logs/api-errors.log with Monolog
- new INSTALL_ROOT/logs folder to store logs
- API errors are logged in api-errors.log
- The general logging file is now at logs/transvision.log
- Monolog library updated to 1.10
- bash scripts no longer create transvision.log because Monolog will create it if it doesn't exist
- logs folder in .gitignore