YARN-1203. Changed YARN web-app proxy to handle http and https URLs from AM registration and finish correctly. Contributed by Omkar Vinit Joshi.
MAPREDUCE-5515. Fixed MR AM's webapp to depend on a new config mapreduce.ssl.enabled to enable https and disabling it by default as MR AM needs
to set up its own certificates etc and not depend on clusters'. Contributed by Omkar Vinit Joshi.


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1524864 13f79535-47bb-0310-9956-ffa450edef68
Merge remote branch 'origin/trunk' into trunk-gd
Merge remote branch 'origin/trunk-gd' into fb-HDFS-4312-trunk-gd