build: Raising requirement for boost to be at least 1.48

This requirement matches the requirement of NFD.

Change-Id: I194a5e81018ab6569615854fa0af9d3a7af4cca8
tests: Making schedule test more resilient

Change-Id: Ibd5a13649e95067c16027ecb909c95e06ff6f1fc
Refs: #1289