Moving to "invoke" framework

- Add "migrate" test

tasks.py

@@ -0,0 +1,63 @@
+# -*- coding: utf-8 -*-
+
+from invoke import task
+
+import os
+
+def localDir():
+    """
+    Returns the directory of *THIS* file.
+    Used to ensure that the various scripts always run
+    in the correct directory.
+    """
+    return os.path.dirname(os.path.abspath(__file__))
+
+def managePyDir():
+    """
+    Returns the directory of the manage.py file
+    """
+
+    return os.path.join(localDir(), 'InvenTree')
+
+def managePyPath():
+    """
+    Return the path of the manage.py file
+    """
+
+    return os.path.join(managePyDir, 'manage.py')
+
+def manage(c, cmd):
+    """
+    Runs a given command against django's "manage.py" script.
+
+    Args:
+        c - Command line context
+        cmd - django command to run
+    """
+
+    c.run('cd {path} && python3 manage.py {cmd}'.format(
+        path=managePyDir(),
+        cmd=cmd
+    ))
+
+@task
+def migrate(c):
+    """
+    Performs database migrations.
+    This is a critical step if the database schema have been altered!
+    """
+
+    print("Running InvenTree database migrations...")
+    print("========================================")
+
+    manage(c, "makemigrations")
+    manage(c, "migrate")
+    manage(c, "migrate --run-syncdb")
+    manage(c, "check")
+
+    print("========================================")
+    print("InvenTree database migrations completed!")
+
+@task
+def test(c):
+    print("hello!")