datastructures: adding bitarray support for self-serializing
gray-crawler: adding bitarray to core code

+ bitarray needs global knowledge from all file systems etc.
+ renamed partition_entry to more descriptive fsdata
+ added helper cleanup function upon error (deduplucating code)
gray-crawler: adding "present" variable to break fs checking logic

+ enables skipping of latter file systems once one has been detected
gray-crawler: refactored MBR code to have better code separation

+ added MBR serialization back to core gray-crawler code
datastructures: cleaned up build.mk, added libbson dependency
gray-crawler: finished ext4 refactoring
gray-crawler: refactored NTFS serialization code
gray-crawler: activating FAT32 partition support

+ MBR code should now recognize FAT32 partitions