Require Boost 1.58 minimum requirement

[anonimal]

I know this may be a bit controversial but the issue at hand is actually more indicative of the need to come to consensus regarding minimum requirements for both projects since we plan on sandwiching kovri with bitmonero.

From #monero-dev:

@anonimal So, clang on https://travis-ci.org/monero-project/bitmonero/jobs/151622228
@anonimal Looks like https://svn.boost.org/trac/boost/ticket/9610
@anonimal and Trusty is building with 1.55
@anonimal So, my question, since Kovri now requires 1.58 minimum, should bitmonero follow suit?
@anonimal I'm going to have to catch up with bitmonero in terms of ARM support, so I wonder where the middle ground will be since we expect to have these two softwares pancaked together

Or maybe there are other solutions we can discuss?

Perhaps we should retitle this ticket into something more generic and use it as an epic 'joining of minimum requirements' thread?