add missing LICENSE files

spotbugs/licenses/LICENSE-logback.txt

@@ -0,0 +1,15 @@
+Logback LICENSE
+---------------
+
+Logback: the reliable, generic, fast and flexible logging framework.
+Copyright (C) 1999-2015, QOS.ch. All rights reserved.
+
+This program and the accompanying materials are dual-licensed under
+either the terms of the Eclipse Public License v1.0 as published by
+the Eclipse Foundation
+
+  or (per the licensee's choosing)
+
+under the terms of the GNU Lesser General Public License version 2.1
+as published by the Free Software Foundation.
+

spotbugs/licenses/LICENSE-slf4j.txt

@@ -0,0 +1,24 @@
+Copyright (c) 2004-2017 QOS.ch
+All rights reserved.
+
+Permission is hereby granted, free  of charge, to any person obtaining
+a  copy  of this  software  and  associated  documentation files  (the
+"Software"), to  deal in  the Software without  restriction, including
+without limitation  the rights to  use, copy, modify,  merge, publish,
+distribute,  sublicense, and/or sell  copies of  the Software,  and to
+permit persons to whom the Software  is furnished to do so, subject to
+the following conditions:
+
+The  above  copyright  notice  and  this permission  notice  shall  be
+included in all copies or substantial portions of the Software.
+
+THE  SOFTWARE IS  PROVIDED  "AS  IS", WITHOUT  WARRANTY  OF ANY  KIND,
+EXPRESS OR  IMPLIED, INCLUDING  BUT NOT LIMITED  TO THE  WARRANTIES OF
+MERCHANTABILITY,    FITNESS    FOR    A   PARTICULAR    PURPOSE    AND
+NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+OF CONTRACT, TORT OR OTHERWISE,  ARISING FROM, OUT OF OR IN CONNECTION
+WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+
+
+