Add 'binstar' information from index metadata to the package metadata

CC @srossross

We should maybe do this a little more generally.
make stored metadata less binstar specific
hide binstar token in conda info output
formatting
update changelog
add ability to only allow system-wise specified channels
typo
remove unused import
better variable name
update changelog
Merge branch 'master' into requests

Conflicts:
	conda/fetch.py