Refactor Auth::initSession method into its own class (SessionInitializer) since the logic will be common to all authentication implementations. Includes tweak to docs of UsersManager API method and additional methods to Auth interface.

Refactor Login controller and auth to be more modular and easier to extend/override. Added extra method to Auth interface and documented Auth interface completely. Created new PasswordResetter class to contain password reset logic.

refs #6257 visitorUUID equal by default for each new Piwik.Tracker

aclocal and autoconf calls are necessary to build the xhprof php extension

Remove contents plugin dependency from actions plugin

refs #6204 wondering if archiving still works when removing this dependency from Actions to Contents plugin. The dependency to the event plugin would be still there. It might work now as I changed Contents plugin to use its own action type recently

Ignore any opcache_invalidate errors

Proxy piwik.php script does not send http headers

Some webhosters with opcache enabled might disable functions like this for security reasons. This should prevent foreign applications from deleting cached things.

Without ignoring this error piwik is unusable and will always shows the error message:
```
There is an error. Please report the message (...)
Warning: Zend OPcache API is restricted by "restrict_api" configuration directive in /piwik/core/CacheFile.php on line 219
```

This call should treat the same way as opcache_reset() in core/Filesystem.php added with faffbd68

Other functions which might be disabled:
- opcache_reset
- opcache_get_configuration
- opcache_get_status
- opcache_compile_file

refs #6284 converted some directive controllers to use controllerAs. Initially I converted nearly of them but noticed it does not always make sense for directive controller so I revert most changes again. For regular controllers it still makes sense which we will use when using ngRoute

refs #5983 mention angularjs update so plugin developers can test their components with latest angularjs version

Updated files to match angular style guide see #5983