Added SHA256 checksum

plugins/python-build/share/python-build/ironpython-2.7.6.3

@@ -1,2 +1,2 @@
-install_zip "IronPython-2.7.6.3" "https://github.com/IronLanguages/main/releases/download/ipy-2.7.6.3/IronPython-2.7.6.3.zip" ironpython
+install_zip "IronPython-2.7.6.3" "https://github.com/IronLanguages/main/releases/download/ipy-2.7.6.3/IronPython-2.7.6.3.zip#dfd00598f4752104f90c248c1662eafbebf7ead24e17531d852ffc32a5a8075b" ironpython
 # FIXME: have not confirmed to install setuptools into IronPython yet