Add simple user-management tool for emailsignin …

Currently, administrators of closed instances need to manually fiddle in
their databases for user-management.
This commit adds a small commandline utility that allows to create and
delete users.

Signed-off-by: Dario Ernst <dario@kanojo.de>

package.json

@@ -79,6 +79,7 @@
     "mattermost": "^3.4.0",
     "meta-marked": "^0.4.2",
     "method-override": "^2.3.7",
+    "minimist": "^1.2.0",
     "minio": "^3.1.3",
     "moment": "^2.17.1",
     "morgan": "^1.7.0",
@@ -103,6 +104,7 @@
     "prismjs": "^1.6.0",
     "randomcolor": "^0.4.4",
     "raphael": "git+https://github.com/dmitrybaranovskiy/raphael",
+    "readline-sync": "^1.4.7",
     "request": "^2.79.0",
     "reveal.js": "~3.6.0",
     "scrypt": "^6.0.3",