Make the Solidity repository standalone.

This commit is the culmination of several months of work to decouple Solidity from the webthree-umbrella so that it can be developed in parallel with cpp-ethereum (the Ethereum C++ runtime) and so that even for the Solidity unit-tests there is no hard-dependency onto the C++ runtime.

The Tests-over-IPC refactoring was a major step in the same process which was already committed.

This commit contains the following changes:

- A subset of the CMake functionality in webthree-helpers was extracted and tailored for Solidity into ./cmake.   Further cleanup is certainly possible.
- A subset of the libdevcore functionality in libweb3core was extracted and tailored for Solidity into ./libdevcore.   Further cleanup is certainly possible
- The gas price constants in EVMSchedule were orphaned into libevmasm.
- Some other refactorings and cleanups were made to sever unnecessary EVM dependencies in the Solidity unit-tests.
- TravisCI and Appveyor support was added, covering builds and running of the unit-tests (Linux and macOS only for now)
- A bug-fix was made to get the Tests-over-IPC running on macOS.
- There are still reliability issues in the unit-tests, which need immediate attention.    The Travis build has been flipped to run the unit-tests 5 times, to try to flush these out.
- The Emscripten automation which was previously in webthree-umbrella was merged into the TravisCI automation here.
- The development ZIP deployment step has been commented out, but we will want to read that ONLY for release branch.

Further iteration on these changes will definitely be needed, but I feel these have got to sufficient maturity than holding them back further isn't winning us anything.    It is go time :-)

test/RPCSession.cpp

@@ -36,15 +36,25 @@ IPCSocket::IPCSocket(string const& _path): m_path(_path)
 		BOOST_FAIL("Error opening IPC: socket path is too long!");
 
 	struct sockaddr_un saun;
+	memset(&saun, 0, sizeof(sockaddr_un));
 	saun.sun_family = AF_UNIX;
 	strcpy(saun.sun_path, _path.c_str());
 
+// http://idletechnology.blogspot.ca/2011/12/unix-domain-sockets-on-osx.html
+//
+// SUN_LEN() might be optimal, but it seemingly affects the portability,
+// with at least Android missing this macro.  Just using the sizeof() for
+// structure seemingly works, and would only have the side-effect of
+// sending larger-than-required packets over the socket.  Given that this
+// code is only used for unit-tests, that approach seems simpler.
+#if defined(__APPLE__)
+	saun.sun_len = sizeof(struct sockaddr_un);
+#endif //  defined(__APPLE__)
+
 	if ((m_socket = socket(AF_UNIX, SOCK_STREAM, 0)) < 0)
 		BOOST_FAIL("Error creating IPC socket object");
 
-	int len = sizeof(saun.sun_family) + strlen(saun.sun_path);
-
-	if (connect(m_socket, reinterpret_cast<struct sockaddr const*>(&saun), len) < 0)
+	if (connect(m_socket, reinterpret_cast<struct sockaddr const*>(&saun), sizeof(struct sockaddr_un)) < 0)
 		BOOST_FAIL("Error connecting to IPC socket: " << _path);
 
 	m_fp = fdopen(m_socket, "r");