Create a cache system (sqlite+.gz files) for all views

## glossaire.sh
Create web/cache/views if missing, delete cache.sqlite to ensure no obsolete cache entries are used

## classes/CacheViews
Class to manage sqlite database and cache entries

## classes/Json
Simplified output, buffer and headers are managed in dispatcher.php

## Views
Modified to not use $locale as a local variable and not die after using Json::output

## contants.php
Added NOCACHE to always served non cached views

## dispatcher.php
Cache management, don't use template for showrepos+json