Ignore the test-generated .yamloo files
net_test: Plug memory leak

1) Make sure that we free `input` in the destructor.

2) Make sure that we free old value of `input` if begin() is
   called more than once.

3) I had to implement a virtual but empty destructor in the
   base class to stop clang++ from warning about a missing
   virtual destructor in the derived class.
Add helpers to implement event emitter
Simplify TCPClient to use event emitter templates
Add default implementation of tcp_test::write()

While there, convert this to use std::string, as opposed to
std::stringbuf, since we are already emitting strings.
Remove pointer from TCPClient to TCPTest
Integrate the event-emitter TCPClient and TCPTest
Implement tcp_connect test
Simplify tcp_connect test so that it does not crash

To be further investigated is the relation between the
crashes and the implementation of event emitter.
Ignore more tests
Merge pull request #59 from TheTorProject/feature/ooni_tcpconnect

Feature: ooni tcpconnect