Merge develop and master branch

[claudep]

We plan to remove the develop branch at some point. We should compare the branches and possibly merge to master some develop commits which have not been integrated until now.

[hugovk]

Looking at the network graph https://github.com/jazzband/tablib/network, I think these are the only ones missing from master:

• Nose link corrected #302
• Delegate type coercion to openpyxl #309
• DataBook().load function params error. #315

[hugovk]

PR #383 cherry picks the commits from #302 and #315.

I've not done #309 because it conflicts.

[claudep]

For #309, I suggest the PR #386.

[claudep]

I think all the code is now in master. I'm not sure if we should delete it or keep it a while for history purposes.