GRN2-6: Added the ability for admins to specify registration method (#520)

* Added the ability to invite users

* Small bug fix

* Added the ability to approve/decline users

* Small bug fixes

* More bug fixes

* More minor changes

* Final changes

app/views/user_mailer/invite_email.html.erb

@@ -0,0 +1,43 @@
+<%
+# BigBlueButton open source conferencing system - http://www.bigbluebutton.org/.
+#
+# Copyright (c) 2018 BigBlueButton Inc. and by respective authors (see below).
+#
+# This program is free software; you can redistribute it and/or modify it under the
+# terms of the GNU Lesser General Public License as published by the Free Software
+# Foundation; either version 3.0 of the License, or (at your option) any later
+# version.
+#
+# BigBlueButton is distributed in the hope that it will be useful, but WITHOUT ANY
+# WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A
+# PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public License along
+# with BigBlueButton; if not, see <http://www.gnu.org/licenses/>.
+%>
+
+  <div style="text-align:center; font-family:'Source Sans Pro', -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Helvetica Neue', Arial, sans-serif">
+    <div style="display:inline-block; background-color:#F5F7FB; border:1px solid #d3d3d3; padding: 25px 70px">
+      <%= image_tag(@image, height: '70') %>
+
+      <h1 style="margin-bottom:30px">
+        <%= t('mailer.user.invite.subject') %>
+      </h1>
+
+      <p>
+        <%= t('mailer.user.invite.info', name: @name) %>
+      </p>
+
+      <p>
+        <%= t('mailer.user.invite.username', email: @email) %>
+      </p>
+
+      <p style="margin-bottom:35px;">
+        <%= t('mailer.user.invite.signup') %>
+      </p>
+
+      <a style="background: <%= @color %>;color: #ffffff; padding: 10px 15px; box-shadow: 0 2px 4px 0 rgba(0,0,0,.25);border: 1px solid transparent;text-decoration:none;" href="<%= @url %>">
+        <%= t('mailer.user.invite.signup_link') %>
+      </a>
+    </div>
+  </div>