add initial compiling heap file to show development
add TravisCI support
implement HashTable class with Python lists holding bucket elements
switch travis CI to use pytest instead of lettuce
switch travis CI to use py.test
Merge branch 'dll' of https://github.com/CharlesGust/data_structures
support package importing in stack package
Merge branch 'hashtable' of https://github.com/CharlesGust/data_structures
Merge branch 'master' of https://github.com/CharlesGust/data_structures