Make the wsgi.conf changes for Python 2.7 in place

`wsgi.conf` is generated each deployment using the user-provided values for script alias, static file directory, # of processes and threads, etc. Using your python27.config file, any changes made to those values are erased when the `wsgi.conf` file is replaced. Instead of replacing the generated file, we can just modify it in place before it is copied into the apache conf directory for use.

PS: Thanks so much for this! It helped me get Python 2.7 set up on EB in no time.