Don't update cache on yum search.

By default, `yum search` will update the repositories' information.
Pacman does not do this, and requires you to do an -Sy operation first.
Since we've implemented -Sy for rpm-based systems, we can mimic that
behavior more closely by forcing yum to not update the cache when
searching (which is also faster).
Merge pull request #14 from xiongchiamiov/dont-update-cache-on-yum-search

Don't update cache on yum search.
Fix Installation note

The use of --no-check-certificate is not recommended; it should be
used only if the user has no way to accept the official Github SSL
cerfiticate. Normally the wget without that options should work fine.
+ Detect RedHat system from /etc/issue
+ OpenSUSE (zypper) support
Fix typo
zypper: Fix option for :Sy
zypper: Support option :Q