Create basic gui (as starting point to build more features onto.)

[pconrad]

Create basic gui that allows

• creating tasks
• deleting tasks
• saving the list to a text file
• saving/loading from serialized file.

~estimated 300

Optional:

• Add buttons for sorting, but those may not work yet.
• Add feature to read from a text file, but that may not work yet.

[erdinckorpeoglu]

fixed in #16