Bug 20259: Shorter JS and CSS rewrite rule

Bug 20259: Shorter JS and CSS rewrite rule

Bug 20187 has changed the JS and CSS rewrite rules to :
RewriteRule ^(.*)_[0-9][0-9]\.[0-9][0-9][0-9][0-9][0-9][0-9][0-9].js$ $1.js [L]
RewriteRule ^(.*)_[0-9][0-9]\.[0-9][0-9][0-9][0-9][0-9][0-9][0-9].css$ $1.css [L]

This patch changes this rules using [0-9]{N} and fusion in one rule.
And espaces the dot in extension js and css.

Test plan :
1) Go to intranet and opac
2) Check CSS and JS are doing well
3) Apply patch changes on our Apache configuration
4) Reload intranet and opac pages (Ctrl + F5)
5) Check CSS and JS are doing well

Signed-off-by: Charles Farmer <charles.farmer@inLibro.com>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Nick Clemens <nick@bywatersolutions.com>