Install grumpy-tools before building grumpy-runtime

`pip2 install grumpy-runtime` fails with the ERROR
#113 (comment)
because it relies on `grumpy-tools`.

`grumpy-tools` packages is specified in `setup.py` as a
dependency, and it doesn't work, because for the build process to
succeed, the dependency should already exist at the time `setup.py`
is executed.

The official workaround is `pyproject.toml` from PEP-518
pypa/pip#2381

Author: abitrolly

grumpy-runtime-src/MANIFEST.in

@@ -8,3 +8,5 @@ global-exclude *.egg-info/*
 global-exclude *__pycache__*
 
 recursive-exclude grumpy-tools-src *.go
+
+include pyproject.toml

grumpy-runtime-src/pyproject.toml

@@ -0,0 +1,2 @@
+[build-system]
+requires = ["grumpy-tools > 0.2.2"]