build: Require java 1.7 and add jndn* libraries as maven repository dependencies

Change-Id: I3cc761d3f67a893bc3f346656b07a87fc60c532c
diff --git a/.gitignore b/.gitignore
index eb380e5..e6a4ae9 100644
--- a/.gitignore
+++ b/.gitignore
@@ -41,6 +41,7 @@
 
 # Gradle cache
 .gradle
+gradle.properties
 
 # Sandbox stuff
 _sandbox