Writable deploy keys (closes #671) (#3225)

* Add is_writable checkbox to deploy keys interface

* Add writable key option to deploy key form

* Add support for writable ssh keys in the interface

* Rename IsWritable to ReadOnly

* Test: create read-only and read-write deploy keys via api

* Add DeployKey access mode migration

* Update gitea sdk via govendor

* Fix deploykey migration

* Add unittests for writable deploy keys

* Move template text to locale

* Remove implicit column update

* Remove duplicate locales

* Replace ReadOnly field with IsReadOnly method

* Fix deploy_keys related integration test

* Rename v54 migration with v55

* Fix migration hell

options/locale/locale_en-US.ini

@@ -401,6 +401,8 @@ valid_until = Valid until
 valid_forever = Valid forever
 last_used = Last used on
 no_activity = No recent activity
+can_read_info = Read
+can_write_info = Write
 key_state_desc = This key has been used in the last 7 days
 token_state_desc = This token has been used in the last 7 days
 show_openid = Show on profile
@@ -995,6 +997,8 @@ settings.add_dingtalk_hook_desc = Add <a href="%s">Dingtalk</a> integration to y
 settings.deploy_keys = Deploy Keys
 settings.add_deploy_key = Add Deploy Key
 settings.deploy_key_desc = Deploy keys have read-only access. They are not the same as personal account SSH keys.
+settings.is_writable = Allow write access
+settings.is_writable_info = Can this key be used to <strong>push</strong> to this repository? Deploy keys always have pull access.
 settings.no_deploy_keys = You haven't added any deploy keys.
 settings.title = Title
 settings.deploy_key_content = Content