cpimport was doing unsigned comparisons for these, but initializing
max to MIN_BIGINT (0x8000000000000002), which is > than any ascii string,
so it would never get set. Changed the init value to 0 for char
types.
cpimport now has the ability to use libmarias3 to read an object from an
S3 bucket instead of a file on local disk.
This also moves libmarias3 to utils/libmarias3.