Revert "Raise CMake requirement to 3.0+"

This doesn't work when the partition manager is enabled because it
uses ECM and ECMConfig.cmake fails with an error if the required
CMake is not less than 2.8.13

Added a note here to remember about this.

This reverts commit 2020eb0eb306f7319b2376b06acb8e242e7b7dc3.
unpackfs: code dedup
unpackfs: check for supported filesystems

Use /proc/filesystems to check if the system
supportes the given source filesystem.
locale: make sure /etc/localtime doesn't exist

If /etc/localtime exists in source image, creating a new symlink will fail
and prevent the installer from doing it's job.
Merge pull request #102 from bbqlinux/master

Supported filesystems check in unpackfs, check for /etc/localtime.
Merge remote-tracking branch 'origin/master' into manjaro