acu124729 fix CLI tools issues
acu124729 remove misleading information from rs_shutdown help
acu124729 update rs_log_level help(add short option for --agent)
acu124729 add usage print on exception support in command_helper
acu124729 return insufficient privilege error message to rs_thunk
acu124729 rs_thunks output error debug information only if there is any
Merge pull request #239 from rightscale/ivory_13_13_acu124729_cli_tool_issues

Fix CLI tool issues