Put /usr/local/bin in nodepool PATH for dib

When we install dib via pip the executables are put in /usr/local/bin
which was not in nodepool's PATH. The PATH is configured by the init
script so update the variable to include /usr/local/bin.

Change-Id: Ie456ecf667d330b925d3168a456d4ac84d1c48f4
Merge "Put /usr/local/bin in nodepool PATH for dib"