Do not mess up with Ido's option in helm module
Remove unnecessary helm configuration code

There options are already the default.
Check if curl is available
Typo & Code style
Merge pull request #670 from toctan/helm-cleanup

Helm cleanup
Fix prelude-open-with on gnu/linux/freebsd
Merge pull request #680 from toctan/fix-open

Fix prelude-open-with on gnu/linux/freebsd
Merge remote-tracking branch 'upstream/master'