Build js file at package time & cleanu sdist

- Stop including the built JS file in the package, instead it
  is built during sdist time (and hence included in the
  wheel). Stolen / inspired from JupyterHub itself.
- setuptool_scm includes *all* checked-in files by default in
  the sdist (pypa/setuptools-scm#190).
  This cleans it out to trim down the size of our sdist
- I think our previous wheel files didn't actually have the
  python package correctly. It is set up correctly now.
- Generated js files are put under a dist/, so we can have
  non-generated static files under static/ in the future. dist/
  is added to .gitignore

.gitignore

@@ -161,3 +161,6 @@ cython_debug/
 
 # JS is everywhere
 node_modules/
+
+# Built files should not be in the package
+static/dist/

MANIFEST.in

@@ -1,4 +1,19 @@
-include LICENSE
-include README.md
-graft jupyterhub_fancy_profiles/templates
-graft jupyterhub_fancy_profiles/static
+# setuptools-scm puts all tracked files here already. We need to
+# prune files we don't want in our sdist, and include generated files
+# Ideally we can simply just *include* files we want, but I have given up
+# on that for now.
+
+# Add generated files
+graft jupyterhub_fancy_profiles/static/dist
+
+# Remove JS files that we won't need when installed
+exclude src/*
+exclude webpack.config.js
+
+# Remove docs & dev time needs we won't need when installed in sdist
+exclude CONTRIBUTING.md
+exclude dev-requirements.txt
+exclude jupyterhub_config.py
+exclude binderhub_config.py
+exclude package.json
+exclude screenshot.png