Created destructive removeTrailingZeros() method on ZString.

testing/zstring_test.cpp

@@ -107,5 +107,9 @@ int main(int argc, char **argv) {
    coreutils::ZString test20(NULL);
    std::cout << "[" << test20 << "]" << std::endl;
    std::cout << "Comparisons with null value: " << (test20 == "true") << std::endl;
+
+   coreutils::ZString test21("10.00000000");
+   std::cout << "Trailing Zeros: " << test21.removeTrailingZeros() << std::endl;
+   std::cout << "                " << test21 << std::endl;
    
 }