Updated util.py functions

Modified parse_map_file() by stripping the newline character from the
header line.
Updated parse_map_file() to include newline character while joining the
header, at the end of the line.
Modified otu_calc.py

Updated sdi function to use math library for calculation instead of
numpy.
Merge pull request #15 from akshayparopkari/master

Updates to util.py and otu_calc.py