catch all throwables in merge transport

If there are streaming errors the requests will just get
hung up and never return if only IOException is catched.
improved speed of bulk inserts in partitioned tables to avoid request timeouts
Clarified naming in InsertFromValuesAnalyzedStatement
Fix symlinks in the crate documentation

1. Symlinks should not contain a full path if possible as
   full paths are not portable
2. The symlink target should be app/plugins/crate-admin/_site - this is
   the only _site I could manage to generate (via ./gradlew dist)
Add a "run" task similar to the runDebug target

Example usage: ./gradlew run -Des.path.home=$(pwd)/sandbox/crate_1/
Note that all system properties are copied, thus -D on the gradle command line will work.
remove Streamable from PartitionName

not used/required
added docs for the user schema feature
added docs about querying user schema tables
add support for using custom schemas
change PartitionName to consider schema names for custom schemas too
correctly handle partitioned table indices and templates
add SCHEMA to non-reserved keywords (according to ISO/IEC 9075)
forbid empty schema on table creation

and streamline exceptions thrown on illegal schema or table name