regenerate thrift code, avoid double buffer-string conversion

This regenerates the cassandra.thrift definition file with the
thrift 0.9.1 compiler + wade's readBinary patch [1]. This patch
makes the autogenerated code use readBinary() to read binary fields
instead of using readString(), avoiding a spurious
buffer -> string -> buffer conversion when parsing cassandra responses.

1: https://issues.apache.org/jira/secure/attachment/12599272/0001-read-binary-strings-with-readBinary-v2.patch