Added ext storage unit tests for writing then reload the mount config
Added password obfuscation for external storage config

Added obfuscation for all "password" options from external storages.
Added unit tests for reading/writing the configuration.
Added IV for ext storage password encryption
Moved external storage mounting code to files_external app

Moved the mounting code for external storage from
OC\Filesystem::initMountPoint to files_external using the
post_initMountPoints hook
Added tests to check mount point list for a target user
Fixed ext storage unit test for groups

Now creating real users and groups for testing external storage mounts
Fixed ext storage password field order issue

The old password field is now preserved in the JSON structure to make
sure that the order is preserved.
This is a quick fix until the UI is fixed to not rely on the PHP array
key order.
Fix typo in mount loading
Lazy load phpseclib in ext storage config
Removed comment
Merge pull request #7794 from owncloud/extstorage-obfuscatepasswords

Obfuscate passwords in ext storage config