Added base File IO module

File IO module added - this will abstract File IO eventually.
squash support

Added some code to check before writing histfile - and to squash if
asked to do so. If no squash, then creates a new name for output by
appending current datetime to histfile name.
Squash action changed to warn and quit

If histfile exists, even if it's empty, and if squashing is not allowed
explicitly, warn and exit program.
Check_space now works on multiple input files

Modified check_space() to check disk space based on an estimate from sum
of file sizes from multiple input files.
Added disk space check

Added code to check for diskspace before output
Input file check

Added code to check for existence and non-emptiness of input files
FileApi logic changed

FileApi now checks file status and takes appropriate action by itself
instead of returning a status
fileApi.check_space() logic change

check_space() now displays error and exits instead of returning the
value of free space needed
Input file(s) existence check + disk space check

Added code to check for existence of input file(s) and also check for
disk space based on sum(input_file_sizes)
Moved and renamed fileapi

Moved fileapi.py from sandbox/ to khmer/ and renamed it to file_api.py
Update file_api usage

import and usage of file_api have been updated in all scripts under
scripts/
Cleaning up files from merge operation
Pylint run

A few errors shown by pylint addressed
Few bug fixes + improvements to file-api

a. Updated check_space docstring
b. Added check_space overload to work with hashSizes
c. Modified check_space statvfs logic to address potential bug from here
(http://stackoverflow.com/questions/51658/cross-platform-space-remaining-on-volume-using-python#comment10259338_2372171)
Overload changed to new method, space check implemented in one script

file-api's check_space for hash tables is no longer an overload.
abundance-dist-single now checks diskspace before hashtable creation.
Disk space checked before hashtable.save() calls
Corrected a copy-paste error

A few scripts use args.k_size and args.min_htsize, others use K and
HT_SIZE. Corrected my code to match up with these variable names
Added base File IO module

File IO module added - this will abstract File IO eventually.
squash support

Added some code to check before writing histfile - and to squash if
asked to do so. If no squash, then creates a new name for output by
appending current datetime to histfile name.
Removed unused imports