Spotless gradle plugin

Added

This MR adds spotless to the gradle build using a configuration file called eclipse-formatter.xml. The following choices were made:

1. Parameters in method signatures and constructors are block-aligned on the column after the opening parenthesis. This is for better readability most prominently in Controller classes.
2. Tabs are used for indentation per Otto's request.
3. JavaDoc parameter and return value documentation is block aligned after the widest parameter name.
4. Any other formatting decisions are based on a template formatting available in Eclipse IDE as 'Java Conventions [Built-in]'

To-do

• @otto Should take a look at whether the gitlab build and tests have to be adjusted for this.
• To have license formatting on I changed the LICENSE.header file, will this interfere with license checking already in the Gradle pipeline?

LICENSE.header

-Queue - A Queueing system that can be used to handle labs in higher education
-Copyright (C) 2016-2019  Delft University of Technology
-
-This program is free software: you can redistribute it and/or modify
-it under the terms of the GNU Affero General Public License as
-published by the Free Software Foundation, either version 3 of the
-License, or (at your option) any later version.
-
-This program 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 Affero General Public License for more details.
-
-You should have received a copy of the GNU Affero General Public License
-along with this program.  If not, see <https://www.gnu.org/licenses/>.
-
-
+/**
+ * Queue - A Queueing system that can be used to handle labs in higher education Copyright
+ * (C) 2016-2019 Delft University of Technology
+ *
+ * This program is free software: you can redistribute it and/or modify it under the terms
+ * of the GNU Affero General Public License as published by the Free Software Foundation,
+ * either version 3 of the License, or (at your option) any later version.
+ *
+ * This program 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 Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License along with
+ * this program. If not, see <https://www.gnu.org/licenses/>.
+ */