Function replace_all

* @brief Replaces (in-place) all occurances of target with replacement. * Taken from: http://stackoverflow.com/questions/3418231/c-replace-part-of-a-string-with-another-string. * @param str - input std::string that will be modified. * @param target - substring that will be replaced with replacement. * @param replecament - substring that will replace target. * @return True if repla