Issues #25,#26,#27. Various issues with CLI

 - rewrite script in Python (embedded JAR won't work on Windows)
 - do not surround classpath with single quote when execution
client via cmd.exe
 - assume current directory when none extracted
Fix checksum generation

Checksums are encoded in UTF-8.
Note: this brings an incompatible change in Liquigraph-core. All
users are advised to undo the migrations played by Liquigraph RC1.