Remove the usage of read_password from library files

The read_password function is defined inside stack.sh
and it cannot be used inside the "public library interface"
provided by DevStack.

Move the calls found inside library files to stack.sh,
following the same pattern of the other calls to read_password.

Change-Id: I8adc6723b677dfac2bef735f660e056c498bf773
3 files changed