[WIP] added endpoint and dao to create invites for users.

Droped token as later code to send email invite can generate
timebased url to send to user. That can then be checked
against configurable time threshold for expiry. Therefore
no need to store a token.

migrations/versions/0023_drop_token.py

@@ -0,0 +1,26 @@
+"""empty message
+
+Revision ID: 0023_drop_token
+Revises: 0022_add_invite_users
+Create Date: 2016-02-24 13:58:04.440296
+
+"""
+
+# revision identifiers, used by Alembic.
+revision = '0023_drop_token'
+down_revision = '0022_add_invite_users'
+
+from alembic import op
+import sqlalchemy as sa
+
+
+def upgrade():
+    ### commands auto generated by Alembic - please adjust! ###
+    op.drop_column('invited_users', '_token')
+    ### end Alembic commands ###
+
+
+def downgrade():
+    ### commands auto generated by Alembic - please adjust! ###
+    op.add_column('invited_users', sa.Column('_token', sa.VARCHAR(), autoincrement=False, nullable=False))
+    ### end Alembic commands ###