update joss paper DOIs (#544)

* add joss badge [skip ci]

* add holmgren2017 doi

* add doi [skip ci]

* add mikofski2017

* update pvlib doi [skip ci]

README.md

@@ -5,8 +5,9 @@ pvlib-python
 [![Build status](https://ci.appveyor.com/api/projects/status/gr2eyhc84tvtkopk?svg=true)](https://ci.appveyor.com/project/wholmgren/pvlib-python-fv2to)
 [![Coverage Status](https://img.shields.io/coveralls/pvlib/pvlib-python.svg)](https://coveralls.io/r/pvlib/pvlib-python)
 [![Documentation Status](https://readthedocs.org/projects/pvlib-python/badge/?version=latest)](http://pvlib-python.readthedocs.org/en/latest/)
-[![DOI](https://zenodo.org/badge/doi/10.5281/zenodo.50141.svg)](http://dx.doi.org/10.5281/zenodo.50141)
+[![DOI](https://zenodo.org/badge/DOI/10.5281/zenodo.1246152.svg)](https://doi.org/10.5281/zenodo.1246152)
 [![Code Health](https://landscape.io/github/pvlib/pvlib-python/master/landscape.svg?style=flat)](https://landscape.io/github/pvlib/pvlib-python/master)
+[![status](http://joss.theoj.org/papers/41187535cad22dd4b076c89b72f874b1/status.svg)](http://joss.theoj.org/papers/41187535cad22dd4b076c89b72f874b1)
 
 
 PVLIB Python is a community supported tool that provides a set of

paper/paper.bib

@@ -43,13 +43,15 @@ @inproceedings{Holmgren2017
 	Author = {William F. Holmgren and Antonio T. Lorenzo and Clifford Hansen},
 	Booktitle = {2017 IEEE 44th Photovoltaic Specialists Conference},
 	Title = {A Comparison of PV Power Forecasts Using PVLib-Python},
-	Year = {2017}}
+	Year = {2017},
+	doi = {10.5281/zenodo.1400857}}
 
 @inproceedings{Holmgren2018,
 	Author = {William F. Holmgren and Clifford W. Hansen and Joshua S. Stein and Mark A. Mikofski},
 	Booktitle = {2018 IEEE 45th Photovoltaic Specialists Conference},
 	Title = {Review of open source tools for PV modeling},
-	Year = {2018}}
+	Year = {2018},
+	doi = {10.5281/zenodo.1401378}}
 
 @article{Louwen2017,
 	Author = {Atse Louwen and Ruud E.I. Schropp and Wilfried G.J.H.M. van Sark and Andr{\'e} P.C. Faaij},
@@ -73,7 +75,8 @@ @inproceedings{Mikofski2017
 	Author = {Mark A. Mikofski and Clifford W. Hansen and William F. Holmgren and Gregory M. Kimball},
 	Booktitle = {2017 IEEE 44th Photovoltaic Specialists Conference},
 	Title = {Use of Measured Aerosol Optical Depth and Precipitable Water to Model Clear Sky Irradiance},
-	Year = {2017}}
+	Year = {2017},
+	doi = {10.5281/zenodo.1403238}}
 
 @article{Polo2016,
 	Author = {J. Polo, S. Garcia-Bouhaben, M. C. Alonso-Garcia},