Fix bas_str and unnecessary transpose in jk.py

[bgpeyton]

Added a new variable in params.py, "bas_str" to hold a string for the basis set. This string is needed in jk.py.

Also fixed an unnecessary transpose done within jk.py.

[codecov[bot]]

Codecov Report

Merging #42 into master will increase coverage by 0.02%. The diff coverage is 85.71%.

@@            Coverage Diff             @@
##           master      #42      +/-   ##
==========================================
+ Coverage   94.73%   94.76%   +0.02%     
==========================================
  Files           6        6              
  Lines         190      191       +1     
==========================================
+ Hits          180      181       +1     
  Misses         10       10