Boost beast

This commit is the beginings of attempting to transition away from
crow, and toward boost::beast.  Unit tests are passing, and
implementation appears to be slightly faster than crow.

Change-Id: Ic8d946dc7a04f514c67b1098f181eee1ced69171
diff --git a/include/ast_video_puller.hpp b/include/ast_video_puller.hpp
index 759aaeb..6cd7f37 100644
--- a/include/ast_video_puller.hpp
+++ b/include/ast_video_puller.hpp
@@ -148,7 +148,7 @@
     boost::asio::async_read(
         dev_video, mutable_buffer, [this](const boost::system::error_code &ec,
                                           std::size_t bytes_transferred) {
-          if (ec != nullptr) {
+          if (ec) {
             std::cerr << "Read failed with status " << ec << "\n";
           } else {
             this->read_done();