add dataframes files

Add Require

standardize method name to be consistent with timearray

Update quandl2df.jl

rename dataframe method

Delete quandl2df.jl

Update dataframe.jl

Attempting to squash commits

Making a few more changes to unscrewup some things
Merge pull request #18 from dreww2/master

Support for DataFrames for Quandl.jl