[ticket/11071] Add fallback if requested style don't exist

PHPBB3-11071
[ticket/12274] Load correct T_TEMPLATE_PATH during update

PHPBB3-12274
[ticket/12274] Fix broke/missing jQuery asset paths in update script

PHPBB3-12274
[ticket/12274] Add core.js to the install footer

Required so phpbb var is defined, as it is used in admin.js.

PHPBB3-12274
[ticket/12281] Disable redis on travis until its fixed again

/home/travis/build/phpbb/phpbb/redis/redis.c:6141:34:
error: unknown type name ‘tsrm_ls’
make: *** [redis.lo] Error 1

The command "sh -c "if [ '$TRAVIS_PHP_VERSION' != 'hhvm' ];
then travis/setup-php-extensions.sh; fi"" failed
and exited with 2 during install.

PHPBB3-12281
Merge pull request #2144 from nickvergessen/travis/disable-redis

[travis/disable-redis] Disable redis on travis until its fixed again
Merge pull request #2136 from Elsensee/ticket/11071

[ticket/11071] Add fallback if requested style don't exist
Merge remote-tracking branch 'vsephpbb/ticket/12274' into develop

* vsephpbb/ticket/12274:
  [ticket/12274] Add core.js to the install footer
  [ticket/12274] Fix broke/missing jQuery asset paths in update script
  [ticket/12274] Load correct T_TEMPLATE_PATH during update