Bug 16088: Introduce Koha::Cache::Memory::Lite to cache the language

Bug 16088: Introduce Koha::Cache::Memory::Lite to cache the language

The goal of this patch is to avoid unecessary flush of the L1 cache on
creating a new CGI object each time C4::Languages::getlanguage is called
without a CGI object.

The new class Koha::Cache::Memory::Lite must be flushed by the CGI
constructor overide done in the psgi file. This new class will ease
caching of specific stuffs used by running script.

Test plan:
At the OPAC and the intranet interfaces:
Open 2 different browser session to simulate several users
- Clear the cookies of the browsers
- User 1 (U1) an User 2 (U2) should be set to the default language
  (depending on the browser settings)
- U1 chooses another language
- U2 refreshes and the language used must be the default one
- U2 chooses a third language
- U1 refreshes and must be still using the one he has choosen.

Try to use a language which is not defined:
Add &language=es-ES (if es-ES is not translated) to the url, you should
not see the Spanish interface.

Signed-off-by: Jacek Ablewicz <abl@biblos.pk.edu.pl>
Signed-off-by: Jesse Weaver <jweaver@bywatersolutions.com>
Signed-off-by: Brendan Gallagher <brendan@bywatersolutions.com>