Call PyInstaller Internally

Instead of calling pyinstaller in another process, we now call it internally using Pyinstaller.main.run.
~ Modified output passing
+ Added handler for sys.stderr
+ Filter using regular expressions in custom sys.stderr handler
+ Check if all modules needed are installed (incl. tkinter)

Support for Python 2 and Tested on Linux

Tested on Python 2 and Linux. Modifications complete and now working as expected.

Use Ephemeral Ports and Call From Outside Project

+ Add a note regarding how to put additional files in the projects root directory
~ Empty ports are now obtained by the OS
~ Fixed calling outside project root
~ When passing a file as an argument convert it to an absolute path
+ Added support for non-utf-8 characters being transferred to the interface
~ Updated requirements.txt

New Method to Add Additional Files

This release is based of the improvement from issue #9 which revised how additional files are added. There are now three methods to add files.

First Stable Release

Now that bugs have been found and fixed, this release should be ready to go.