* src/*: Move files generated by thrift-compiler to thrift subfolder.
* Makefile: new file, builds on Mac OS X
* src/zipkin_import.cpp: empty main file.
Update with command line options and thrift client code.

* src/import_csv.cpp: New, currently empty file.

* src/thrift_client.cpp: New, implements a client that can send LogEvents to
          a Scribe server.

* src/zipkin_import.cpp:
  (main): Parse command line options.

* src/zipkin_import.h: New, declarations for classes added in thrift_client.cpp.