Upgrading exports (#283)

* Upgrading export capabilities
* Only apply sqlite hacks for sqlite

This fixes #250, #246
Adds export.py to save CTFs without needing to actually spin up CTFd
Also forcing charset properly for MySQL

export.py

@@ -0,0 +1,23 @@
+from CTFd import create_app
+from CTFd.utils import ctf_name, export_ctf
+
+import datetime
+import sys
+import shutil
+import zipfile
+
+
+app = create_app()
+with app.app_context():
+    backup = export_ctf()
+
+    if len(sys.argv) > 1:
+        with open(sys.argv[1], 'wb') as target:
+            shutil.copyfileobj(backup, target)
+    else:
+        ctf_name = ctf_name()
+        day = datetime.datetime.now().strftime("%Y-%m-%d")
+        full_name = "{}.{}.zip".format(ctf_name, day)
+
+        with open(full_name, 'wb') as target:
+            shutil.copyfileobj(backup, target)