Update from v0.4 to v0.5 (pre-release version)

* Adding block location cache to HdfsTable in order to speed up getBlockMetadata().
  - we're now pre-computing and caching the result of HdfsTable.getBlockMetadata() on a per-partition basis
  - to make the cache more compact, we're collecting pools of unique strings:
    file names are collected per partition and ip/port strings are collected per table
* File Permission error should be returned the shell and visible to the user
  Log that an error occurred opening the file and call get_log in the shell when an insert fails.
  Don't unregister query in ImpalaServer::Wait so we can recover error message later.
* Bumping version to v0.5
* Make $IMPALA_HOME/shell hold python modules.
* Date diff had the order backwards.
* Code changes to build against thrift 0.9.0
* IMPALA-15: UNIX_TIMESTAMP format behaviour deviates from Hive when format matches a prefix of the time value
  Truncate datetime value to length of format if necessary.
* Move to LLVM 3.2