Use the regular bash_profile on CentosVM

The bash_profile file I've been using everywhere else is suitable for
the CentosVM, so use that.  This:

- Makes some whitespace and other minor changes (use `[[ ... ]]` since
  it's the Bash profile file so Bashisms are clearly okay, etc).
- Doesn't define `http_proxy` or `ftp_proxy` to be empty strings.  No
  idea why I'd want to do that.
- Doesn't append `~/bin` to `PATH`.  That belongs in .profile if it's
  going to go anywhere.
- Doesn't define `LD_LIBRARY_PATH`, which similarly belongs in .profile,
  and really shouldn't routinely include `.`.