basic implementation of _dump endpoint
Merge branch 'master' into dump

Conflicts:
	src/main/java/crate/elasticsearch/action/export/TransportExportAction.java
creating default dump dir if it does not exist
Merge branch 'master' into dump
moved dump classes to specific packages; added tests; some readme notes
Merge branch 'dump' of github.com:crate/elasticsearch-inout-plugin into dump
replaced generated class javadoc
made dump section in readme.txt more readable
replaced generated class javadoc with something usefull
removed HTTP GET handlers for _dump endpoint
overriding transportAction in concrete implementation