Completed requirements specification (PyQt4 and requests) and improved setup.py

[davidlj95]

Changelist:

• Fixed setup.py to work without having PyQt4 installed (so you can install it later):
  • Created hashmal_lib.entry_points module to contain entry points
  • Moved hashmal_lib.gui_utils module's constant hashmal_entry_points to previously created file
    Contains a reference to it to mantain constant in both modules
  • Changed setup.py import from hashmal_lib.gui_utils import hashmal_entry_points to from hashmal_lib.entry_points import hashmal_entry_points
  • Moved hashmal_lib.__init__ module imports to inside the class (so doesn't import PyQt4 until instanced)
• Added requests module as a requirement in requirements.txt
• Explained in README.md the PyQt4 requirement and a basic how-to to install the module
• Added build/ and dist/ to .gitignore