Remove confusing error message

The actual error message is there, and is more helpful.
Fix conda info -a when there are no user site dirs
pscheck: The command might not have 'conda ' at the start

Should fix #888.
Merge branch 'master' of github.com:conda/conda
search: don't mark packages from other platforms as being installed or cached
Update CHANGELOG
Warn if the hint generation might take a while
Use a progress bar for --alt-hint
Use a progress bar for the unsatisfiable packages hint generation

Unfortunately, this runs through several passes until it finds an answer, so
the progress bar may reset when it is finished and run through a larger number
of tries. The number of tries remaining is printed, though, so it should give
users a much better idea of when they should give up.
Fix variable initialization
Don't use TemporaryFile in try_write

TemporaryFile tries thousands of times before if fails, making it really
slow. Just use open and unlink.

Fixes #896.
Ignore InsecureRequestWarning when ssl_verify is False
Merge pull request #892 from daineseh/master

Fix variable initialization
conda remove removes features tracked by removed packages

So for instance, conda remove mkl now removes the mkl feature.

Fixes #894.
Merge branch 'master' of github.com:conda/conda