Updates to installation and packaging pages

Includes:

* Slightly fuller install instructions for Ubuntu and others
* Changes to the Windows and OSX packaging pages, primarily to prevent the packager from including the entire source folder in the distributed output
I think it would be easier to allow the user to specify the extensions in a list  like this::

def addDataFiles():
		allFiles = Tree('../kivy/examples/demo/touchtracer/')
		extensions = ['.png', '.kv', '.jpg', '.gif', '.wav', '.ico']
		extraDatas = []
		for file in allFiles:
			dot_pos = file[0].rfind('.')
			if dot_pos and file[0][dot_pos:] in extensions:
				print "Adding datafile: " + file[0]
				extraDatas.append(file)
		return extraDatas