Update Giraph-Gora documentation and make it available from giraph.a.o
GIRAPH-947: Compilation error with hadoop 2.5.x fixed.

1. Munge symbol 'STATIC_SASL_SYMBOL' was added.
2. STATIC_SASL_SYMBOL was added to all build profiles, except hadoop_2 and hadoop_snapshot. Profile 2.1.1-SNAPSHOT is not munge-free anymore.
3. Default hadoop version of profile hadoop_2 was changed: 2.2.0 -> 2.5.0
GIRAPH-946. Upgrade to Gora 0.5 (Renato Javier Marroquín Mogrovejo via rvs)