Fix conda search --platform to work in all cases

Fixes #524.
Merge branch 'master' of github.com:conda/conda
change default
update pip warning message
Don't show the platform in the conda search results

You can only search for one platform at a time, so this is redundant.
Merge branch 'master' of github.com:conda/conda
Don't include command suggestions more than once
Fix finding of external commands
fixed typo: thanks asmeurer
Fix --dry-run when always_yes is set
add debug information
* remove condarc warnings: issue #526#issuecomment-33195012
cleanup
	condarc
Merge commit '39ffee737acec22270b50e428f8c9e9bb2a1ba35'
Merge branch 'origin/remove_condarc_warnings'

Conflicts:
	CHANGELOG.txt
tMerge branch 'origin/remove_condarc_warnings'

Conflicts:
	CHANGELOG.txt