Older versions of Stata dta files are not readable
Checking some older verions, and found that the versions that are not tested cannot be imported using `from_stata` or `StataReader`.  For example, 

http://fmwww.bc.edu/ec-p/data/wooldridge2k/401ksubs.dta

produces an error when trying to parse the header. This file is version 105.  As far as I know, there are on online docs for older versions of dta, so it probably isn't worth trying to support them.

The simplest fix is to just modify the versions that are supported to only include 113+, which still covers a long history.
