Cleanup: Migrate Http1:: Parser child classes to C++11 initialization

Cleanup: Migrate Http1:: Parser child classes to C++11 initialization

Also, add move semantics to Http1::RequestParser. This apparently will
make the clear() operators faster as they no longer have to data-copy.
At least, one the base Parser class supports move as well.

It also consists a small experiment to see if virtaul destructor alone
allows automatic move constructor to be added by the compiler.