<rdar://problem/11538779> Fixing issues where Python scripts were not able to...

<rdar://problem/11538779> Fixing issues where Python scripts were not able to read user input and/or display output to the user in certain situations - This fix introduces a Python InputReader manager class that mimics the behavior of the interactive interpreter in terms of access to I/O and ensures access to the input and output flows

llvm-svn: 158124