Replace use of boost/assign/list_of with more readable C++-11 initializer lists in rpc/rawtransaction.cpp

Summary:

Sorry, had to redo this diff as something got totally screwed up in phabricator.

Since bitcoin sources now use C++11, there is no need to use the less-readable boost::assign::list_of. C++11 initializer lists are more readable and maintainable

Test Plan: make check and rpc-tests.py

Reviewers: freetrader, deadalnix, #bitcoin_abc

Reviewed By: deadalnix, #bitcoin_abc

Differential Revision: https://reviews.bitcoinabc.org/D463