buildPythonApplication: use new function for Python applications

[FRidh]

In 49c6893 buildPythonApplication was introduced.
This commit converts (almost) all occurrences of buildPythonPackage with buildPythonApplication except those in

• pkgs/top-level/python-packages.nix
• pkgs/development/python-modules/

[mention-bot]

By analyzing the blame information on this pull request, we identified @aszlig, @roblabla and @bosu to be potential reviewers

[FRidh]

cc @domenkozar

[dezgeg]

I guess the namePrefix = "" should be removed at the same time?

[FRidh]

@dezgeg Good point. But that seems a bit harder to automate though.

[dezgeg]

Maybe something like (untested):

for f in $(git diff --name-only); do
    sed -e '/namePrefix *=/d' -i $f
done

[FRidh]

Will need to add buildPythonApplication to docs.

[FRidh]

Having namePrefix=""; inside buildPythonApplication is no problem. They can be removed later.