new options for jail introduced addfailregex/addignoreregex #867

feature request (#867): new options for jail introduced `addfailregex`/`addignoreregex`: extends regex specified in filter (opposite to `failregex`/`ignoreregex` that overwrites it);

BF: failregex declared direct in jail was joined to single line (specifying of multiple expressions was not possible);

You're wrong here, the `failregex` overwrites the option with same name comming from filter.
`addfailregex` does not (because it not available for filter).
See the test case from 143915212196a70d44b7ee30521977ff05c3be69: 
- jail `[test1addfailregex]` has a following entry taken from filter:
```
['set', 'test1addfailregex', 'addfailregex', '<IP>']
```
- jail `[test2failregex]` has not.