ENH: Add support for file paths in DistancMatrix
ENH: Add support for file paths in DistancMatrix

This object can now load data given a file path or given an iterable of
strings.

Fixes #233

SamStudio8/scikit-bio,wdwvt1/scikit-bio,johnchase/scikit-bio,colinbrislawn/scikit-bio,corburn/scikit-bio,anderspitman/scikit-bio,jairideout/scikit-bio,Achuth17/scikit-bio,Achuth17/scikit-bio,kdmurray91/scikit-bio,anderspitman/scikit-bio,averagehat/scikit-bio,Kleptobismol/scikit-bio,jensreeder/scikit-bio,wdwvt1/scikit-bio,xguse/scikit-bio,gregcaporaso/scikit-bio,averagehat/scikit-bio,demis001/scikit-bio,Jorge-C/bipy,colinbrislawn/scikit-bio,Kleptobismol/scikit-bio,demis001/scikit-bio,Kleptobismol/scikit-bio,gregcaporaso/scikit-bio,kdmurray91/scikit-bio,jensreeder/scikit-bio,corburn/scikit-bio,johnchase/scikit-bio,xguse/scikit-bio,SamStudio8/scikit-bio,jdrudolph/scikit-bio,jairideout/scikit-bio,jdrudolph/scikit-bio