A bare minimal Makefile project

Consist of:
1. Root level Makefile
2. src level Makefile
3. header and source files in src
4. .gitignore to ignore compile results
Migrate headers out to include

Make it easier to cross compile header files. Make way for unit test.
Added a test that make sense

Assert the expected result of hello library
Finish the basic feature

Finish the feature that fulfills the unit test
Added test and declaration of "foo"

Declared and test the new foo function
Finished foo as specified