Create sftp.php

Adapter for SFTP using the pure php SSH library phpseclib
Update apps/files_external/appinfo/app.php

Adding support for SFTP
Update apps/files_external/lib/config.php

Adding support for SFTP mounts
Update apps/files_external/lib/sftp.php

Added checks for host keys and added exceptions thrown if constructor fails.
Update apps/files_external/lib/sftp.php

Added a little better exception handling, hopefully making it a little more robust
Update apps/files_external/lib/sftp.php

Added copyright notice
Added phpseclib to files_external as 3rdparty
Update apps/files_external/lib/sftp.php

Updated to using local 3rdparty + added a few missed braces.
Update apps/files_external/lib/sftp.php

Created test() function as per @pull/1031
Added creation of dir for shared file env encryption keys
Added comment to use multiKeyEncrypt
Merge branch 'master' into files_encryption
Added two hooks: pre_unshare and pre_unshareAll, useful for files_encryption
Merge branch 'master' into files_encryption
Adding sharing support: added new method in Keymanager setShareKey()
Added notes in proxy{} and stream{} pointing to share support
add trash button to web interface
listen to post delete event to allow the trash bin to create a copy of the version first
rename "publicListView" option to "disableSharing", this is more meaningful also because it is not only useful for the public list view
call the trash bin view
introduce option to disable download action
first version of the trash bin app