[TIMOB-6749] iOS: 'markdown' is now 'markdown2' in python module for build.py

In the [wiki documentation](https://wiki.appcelerator.org/display/guides/iOS+Module+Development+Guide#iOSModuleDevelopmentGuide-PackagingyourModule) for developing iOS modules, it notes that it is necessary to install the [python module 'markdown'](https://github.com/trentm/python-markdown2) to package your module. In TiStudio 1.0.7, this can now be done from the wizard. Unfortunately, the build.py script for packaging the module references this library as *markdown* when it now needs to be referenced as *markdown2*. Module packaging will end in error. The area in build.py that would need to change is (starting at line 54)

import markdown
documentation = []
for file in os.listdir(docdir):
	if file in ignoreFiles or os.path.isdir(os.path.join(docdir, file)):
		continue
	md = open(os.path.join(docdir,file)).read()
	html = markdown.markdown(md)
	documentation.append({file:html})

and it needs to be changed to the following to support the markdown2 import

import markdown2
documentation = []
for file in os.listdir(docdir):
	if file in ignoreFiles or os.path.isdir(os.path.join(docdir, file)):
		continue
	md = open(os.path.join(docdir,file)).read()
	html = markdown2.markdown(md)
	documentation.append({file:html})

This, though, would create a failure in backwards compatibility. I'll leave that solution to someone better versed in python scripting.