consolidate --log and --log-file

[qwcode]

from the 0.7 changelog

"pip now logs to a central location by default (instead of creating pip-log.txt all over the place) and constantly overwrites the file in question. On Unix and Mac OS X this is '$HOME/.pip/pip.log' and on Windows it’s '%HOME%\pip\pip.log'. You are still able to override this location with the $PIP_LOG_FILE environment variable. For a complete (appended) logfile use the separate '--log' command line option"

my biggest problem with this, is that "--log" and "--log-file" mean the same thing (by name) to humans, so it's immediately confusing. it's true that "--log-file" is hidden in the help, but people end up finding it (in order to control it).

Here's the requirements for logging as I see it:

1. have a consistent default log location (i.e. what we currently use) that can be altered with the one and only log option. (either --log or --log-file, but not both)
2. have it not append by default (for space issues?), with an option to append (--log-append)
3. have it honor console --verbosity; (with maybe an optional --log-verbosity if you want different verbosity for logging vs console output)
4. the console and log file should be logging the same thing; as it is --log-file is only logging when there's errors

related issue: #350