Public interface for hashing which also works with legacy ownCloud hashes and supports updating the legacy hash via a passed reference.

Follow-up of https://github.com/owncloud/core/pull/10219#issuecomment-61624662
Requires https://github.com/owncloud/3rdparty/pull/136

Resolves https://github.com/owncloud/core/issues/10991 failure 4

Will only work after tomorrow

This adds some security utilities to core including:
- A library for basic crypto operations (e.g. to encrypt passwords)
- A better library for cryptographic actions which allows you to specify the charset
- A library for secure string comparisions

Remove .htaccess

Remove .htaccess

Fix typo

Add public API

Use timing constant comparision

Remove CBC constant

Adjust code

Remove confusing $this