Revert "Squashed 'qa/rpc-tests/python-bitcoinrpc/' content from commit e484743"

This reverts commit 260cf5c0a4754be39b05f6a247b8a354de7eced6.
build: fix explicit --disable-qt-dbus

It worked in the auto/yes cases, but an explicit disable actually forced
it on.
Merge pull request #3878

da0b9d4 Revert "Squashed 'qa/rpc-tests/python-bitcoinrpc/' content from commit e484743" (Johnathan Corgan)
Merge pull request #3881

a22e9a3 build: fix explicit --disable-qt-dbus (Cory Fields)
Split up CheckBlock in a block and header version
Split AcceptBlockHeader from AcceptBlock.

Also modify some connection logic to deal with non-full blocks in the index.