Added build command

cli_test.go

@@ -14,9 +14,12 @@ func TestCLI(t *testing.T) {
 	}
 
 	tests := []cliTest{
-		{[]string{}, 1},
-		{[]string{"invalid"}, 1},
+		{[]string{}, 2},
+		{[]string{"invalid"}, 2},
 		{[]string{"system"}, 0},
+		{[]string{"build", "non-existing-directory"}, 1},
+		{[]string{"build", "examples/hello/hello.q"}, 2},
+		{[]string{"build", "examples/hello", "--invalid"}, 2},
 	}
 
 	for _, test := range tests {