also fetch pre-5.0 versions and 5.7.x now
database options now easily configurable
* db connecition now configurable
* bug pages from bugs.mysql.com are cached locally now
* support for different HTML style in pre-5.0 changelogs
* lowest known oracle bug being refered to is in the 300K range;
  lowered threshold to 200K
make sure bug_html cache directory exists
ignore bug chache directory