util/util.c: adding an error printer

+ no return value should go ignored
util/util.c: remove color lib dependency
gammaray: migrate from f* family to lower level IO functions

+ Examples: fopen --> open,
            fseeko --> lseek64,
            fread --> read,
            fwrite --> write,
            fclose --> close

+ This should fix Android builds (do not currently respect #define _FILE_OFFSET_BITS 64)

+ ext4 has been tested for regressions (gray-crawler work cycle)

- gray-inferencer, gray-ndb-queuer, gray-fs still need testing
- ntfs untested anywhere
nbd/nbd.c: safer handling of lssek64 return values
gray: safety checks by clang
Merge pull request #32 from cmusatyalab/safe-64bit-crawler

Safe 64bit crawler
gray-crawler: forgot to remove variable post-merge
Seek to the beginning of the disk file before probing.

cc @theonewolf
Add stubbed GPT support for #14.

cc @theonewolf

+ Integrated into build.
+ Loads the start of the GPT and checks the signature when probing.
Fix use of `pt->pt_info` for #14.

cc @theonewolf
Store signature as 64 bits rather than a byte array for #14.

cc @theonewolf
Add struct and print GPT header for #14.

cc @theonewolf
Print guid.
s/partition_table/mbr_partition_table for #14.
Add gpt_partition_table_entry for #14.

cc @theonewolf
Current GPT state for #14 ready for Android.

cc @theonewolf

I don't think the BSON is the exact format the other components of
GammaRay expects, but the current state is enough to get some
output from GPT's.

This commit:
+ Prints GUID's as gdisk.
+ Gets the next partition.
+ Adds pt and pte serialization.
Merge.