switch to gradle

gradle files added
gradle: plugins added
build: files added
.travis.yml: gradle cache stored
distribution: tar and zip file stuff added
broker/build.gradle: osgi plugin added
build: bintray upload added
pom: files removed
distribution: assembly.xml removed
gradle: test ouput added to sub builds
.editorconfig: gradle files added
build: wrapper task added
osgi: added to h2_ and mapdb_storage
gradle: files cleaned
build.gradle: jars used for tar/zip

.gitignore

@@ -1,3 +1,5 @@
+/build
+*/build/
 /target/
 /parser/target/
 /benchmarking/target/
@@ -31,7 +33,6 @@ broker/runner
 .mtj.tmp/
 
 # Package Files #
-*.jar
 *.war
 *.ear
 
@@ -43,3 +44,4 @@ broker/nb-configuration.xml
 broker/nbactions-Server.xml
 
 maven-metadata.xml
+/.gradle/