Use optional environment variable BRCLI_HOME for location of login config file
Use optional environment variable BRCLI_HOME for location of login config file

- If the BRCLI_HOME env var does not, reverts to using HOME.
- Now creates .brooklyn_cli with file mode 600 instead of 666.
- Reports errors to STDERR via error_handler.ErrorExit

lloyddave/brooklyn-cli,lloyddave/brooklyn-cli,brooklyncentral/brooklyn-cli,brooklyncentral/brooklyn-cli