added options for labeling, changed sweep script name, updated tests to reflect changes

fixed syntax error in consume output
changed output freq for consume
groups mode in sweep now splits input file as well
added label counts output
outdir option
suppressed warning when read len less than kmer len
suppressed warning message when read length less than k-mer length
added help strings to more arguments for docs
fixed error in printed output of number reads labeled
new test for sweep
added html target for coverage
stripped out unused write_seq function
fixed error handling for IOError when flushing individual buffer
fixed test_sweep_reads_2 to cover all cases of buffer flush, added extra test to cover label-by-group
removed extraneous del statement
checked in new test file for sweep_test_3
silence pylint noise, switch to new-style objects