Update ODatabaseRecordAbstract.java

For backward compatibility.
Due to many existing APIs to save document by calling default doc.save() without specify cluster name, if create multi clusters, it will do round robin to shard document equally in each cluster, no way to specify cluster to store, especially in distributed mode,

To solve this issue, i can create a hook to change cluster id for each document to give the fix cluster Id to store and set DISTRIBUTED_EXECUTION_MODE to SOURCE_NODE.
Update ODocument.java

Add to toMap function for ODocument
add gitter badge to README.md
Merge pull request #2623 from phpnode/patch-1

add gitter badge to README.md
Report that channel is not connected if the socket is closed.
New test case to understand issue #2582
Fixed issue #2582 about distributed addEdge for regular edges
Minor: pre-allocated 2k of stream for serialization
Fixed issue ETL #1 (https://github.com/orientechnologies/orientdb-etl/issues/1)
OOM is thrown if memory is not allocated.
Merge remote-tracking branch 'origin/1.7.8' into 1.7.8
Fixed issue #2582
Read lock is release if socket is closed.
Merge remote-tracking branch 'origin/1.7.8' into 1.7.8
implemented script for backup database with full freeze and lvm support
Fixed issue #2659
Nothing compression avoid to copy bytes if not needed
Console: fixed returning of result in case of error
fixed backup.sh for support plocal and remote lvm
Merge pull request #2662 from rtc-draper/fixsock

Report that channel is not connected if the socket is closed.