build: Fixing dependency detection

When detecting location of the library, `includes` and `libpath`
variables must be used instead of `cxxflags` and `linkflags` to specify
path to includes and path to the libraries.

Change-Id: I81048a9c80f3e743630a0e80231fc6290aa782ec
src: Remove unnecessary uses of boost::cref in make_shared and replace boost::cref/boost::ref with just cref/ref

In some cases, due to argument-dependent lookup, it is necessary to use
ndn::ref, instead of just ref.

Change-Id: I682180a007609535855f77511b49622154ad4f11
Refs: #1591
fw: Strategy::sendInterest allows changing Nonce

This commit also includes some tweaks in forwarding pipelines.

refs #1596

Change-Id: I65a4129be24089357b28fa9d35a3451e0d9ae258
build: Enabling ability to use precompiled headers and some other build fixes

Change-Id: If2b216e5674fc762338929026733f3dcb801bb1b
Refs: #1588