Support for /etc/fstab and mounting partitions on boot

[jdetter]

Right now, Chronos will search for the first EXT2 file system on the disk and use that as the root file system and then mount a memory based file system on /dev (creating /dev first if necessary). Support needs to be added for an fstab file so that different partitions can be mounted at different places in the file system. This will also be a precursor to adding support for booting with GRUB2.

[jdetter]

Basic support in dbfe42c, also needed to add support for the infamous strtok_r.