Added reference to Jersey for RESTful services.

Added Api package.
Added BlocksResource as first candidate for API implementation.

src/api/BlocksResource.java

@@ -0,0 +1,28 @@
+package api;
+
+import javax.ws.rs.GET;
+import javax.ws.rs.Path;
+import javax.ws.rs.Produces;
+import javax.ws.rs.WebApplicationException;
+import javax.ws.rs.core.MediaType;
+
+import repository.DataException;
+import repository.Repository;
+import repository.RepositoryManager;
+
+@Path("blocks")
+@Produces(MediaType.APPLICATION_JSON)
+public class BlocksResource {
+
+	@GET
+	@Path("/height")
+	public static String getHeight() 
+	{
+		try (final Repository repository = RepositoryManager.getRepository()) {
+			return String.valueOf(repository.getBlockRepository().getBlockchainHeight());
+		} catch (Exception e) {
+			throw new WebApplicationException("What happened?");
+		}
+	}
+
+}