Added better logging with different logging levels

Creates a (new) logfile stored in the root folder, named `ice.log`. This can easily be pointed to the old `log.txt` however.

By using the `logging` module, it is easy to decide which information you want store in the stream handler (terminal output) and file handler (logfile).

Example terminal/logfile output:
[marcus@archlinux-desktop Ice]$ python2 ice.py 
2013-12-23 23:57:03,707 (ice) INFO: Starting Ice
2013-12-23 23:57:03,710 (ice) INFO: Skipping DS (no emulator provided)
2013-12-23 23:57:03,710 (ice) INFO: Skipping SNES (no emulator provided)
2013-12-23 23:57:03,711 (ice) INFO: Skipping PS2 (no emulator provided)
2013-12-23 23:57:03,711 (ice) INFO: Skipping PS1 (no emulator provided)
2013-12-23 23:57:03,711 (ice) INFO: Skipping NES (no emulator provided)
2013-12-23 23:57:03,711 (ice) INFO: Skipping Dreamcast (no emulator provided)
2013-12-23 23:57:03,711 (ice) INFO: Skipping GBA (no emulator provided)
2013-12-23 23:57:03,712 (ice) INFO: Skipping Genesis (no emulator provided)
2013-12-23 23:57:03,712 (ice) INFO: Skipping Gamecube (no emulator provided)
2013-12-23 23:57:03,712 (ice) INFO: Skipping N64 (no emulator provided)
2013-12-23 23:57:03,712 (ice) INFO: Skipping Wii (no emulator provided)
2013-12-23 23:57:03,712 (ice) INFO: Skipping Gameboy (no emulator provided)
2013-12-23 23:57:03,713 (ice) INFO: Running for user 20421584
2013-12-23 23:57:03,713 (ice) INFO: Downloading grid images
2013-12-23 23:57:03,714 (ice) INFO: Ice finished

Close the window, or hit enter to exit...

Example terminal/logfile output with error:
2013-12-24 00:17:54,460 (ice) INFO: Starting Ice
2013-12-24 00:17:54,463 (ice) ERROR: Stopping
2013-12-24 00:17:54,464 (ice) ERROR: There was a problem with '[T] location' in emulators.txt
2013-12-24 00:17:54,464 (ice) ERROR: The key 'location' is missing
2013-12-24 00:17:54,464 (ice) ERROR: Cannot read file ''. Ensure that the file exists, and that the path is spelled correctly.
2013-12-24 00:17:54,465 (ice) ERROR: Traceback (most recent call last):
(... A BUNCH OF TRACEBACK, REMOVED IN EXAMPLE ...)
ConfigError: "[T] location || Cannot read file ''. Ensure that the file exists, and that the path is spelled correctly."


Everything should be working without problem, as I've just replaced the new logging methods with the old ones.