ASTERIXDB-1153: Determine build information at runtime

Very simple API. Just do a GET against /admin/version and get all of the build-time git info in JSON.

Change-Id: Ie392eb0cdbd25f2f4679fba12aae4c7a496e9637
Reviewed-on: https://asterix-gerrit.ics.uci.edu/468
Tested-by: Jenkins <jenkins@fulliautomatix.ics.uci.edu>
Reviewed-by: Till Westmann <tillw@apache.org>
diff --git a/.gitignore b/.gitignore
index 189af35..b75b189 100644
--- a/.gitignore
+++ b/.gitignore
@@ -22,3 +22,4 @@
 .idea/
 asterix.ipr
 asterix.iws
+git.properties