refs #1:
- added argument to force file overwrite
- changed exit to rise exception on file name conflict
refs #2:
- added posibility to provide full path to file
Merge pull request #43 from Eloar/1_issue

Possibility to overwrite downloaded file
Merge pull request #44 from Eloar/2_issue

Added posibility to save movie to custom file name
Merge branch 'master' into 4_issue

Conflicts:
	pytube/models.py