Add files section to app.src for hex.pm packaging

Include build scripts (do_cmake.sh, do_build.sh) and other necessary
files so they are packaged when publishing to hex.pm.

Author: benoitc

src/erlang_python.app.src

@@ -14,5 +14,16 @@
     ]},
     {modules, []},
     {licenses, ["Apache-2.0"]},
-    {links, [{"GitHub", "https://github.com/benoitc/erlang-python"}]}
+    {links, [{"GitHub", "https://github.com/benoitc/erlang-python"}]},
+    {files, ["rebar.config",
+             "do_cmake.sh",
+             "do_build.sh",
+             "README.md",
+             "LICENSE",
+             "CHANGELOG.md",
+             "src",
+             "c_src",
+             "docs",
+             "examples",
+             "test"]}
 ]}.