First step in Epp's argument

Not sure, but it seems that one needs the Nagata condition to make this
first step work.
Remove mistakes from previous commit
Constructing flat local maps with given residue field

Small improvement earlier exposition + more precision in case the
residue field extension is separable algebraic
References related to Epp's paper
Additional material for section on Epp's paper

Some of this material is wrong, will be changed etc.
Add proof of lemma on switching to strict henselizations
Standard material about Galois extensions of ff of dvrs
Krasner's lemma
Get separable extension in the first case of Epp's argument

Of course this doesn't work if you started just taking a pth
root out of a uniformizer of the base dvr
First version of second part Epp's proof (char p case)
A bit more about Galois theory

We've so far considered all field theory to be part of the basic
requisites for the Stacks project. But we could have a bit more
detail in the presentation of this material.
Level lowering in Epp's proof

The most intricate part is now done. Tried to make the mized
characteristic part of the proof resemble the characteristic p
part of the proof. It is clear that it works, but it is kind of
annoying to write down.
Statement of Epp's theorem and reduction steps

Unfinished
Taking invariants of finite groups acting on rings
Final arguments in the proof

This clearly works, but it is still quite rough.
Merge branch 'develop'

We finished the proof of Epp's theorem on the develop branch and
it makes sense to merge it back into the master branch.