* feat(install, svn): remove svn
Remove everything related to svn.
Rename uoj-svn-lib to uoj-data-lib.
Save preparing problem data to /var/uoj_data/prepare/problem_id.
* Typo: uoj_date -> uoj_data
* add: backward compatibility
BREAKING CHANGE: Preparing problem data location is changed
You need to move files from /var/svn/problem/{id}/cur/{id}/1 to
/var/uoj_data/upload/{id}
In order to support PHP7, change the way to operate database. PHP7
removed the mysql extension, so the old way to operate database is
not usable. This commit use a new way to operate database.
BREAKING CHANGE: the way to operate database has changed.