Ban time incr

New feature "automatically exponential increasing ban time".
WARNING: by first start the server upgrades sqlite database (table "bans" will recreated with another schema);
Option "bantime.increment" in jail.conf allows to use database for searching of previously banned ip's to increase a default ban time using special formula, by default each next ban increase banTime * 1, 2, 4, 8, 16, 32...
see "jail.conf" for some other options of "bantime.___";
additional we can configure a little randomization of ban time, to prevent "clever" botnets calculate exact time IP can be unbanned.

@kwirk, I don't see the implementation should be "overcomplicated" here, why did you mean it?
- for 2 parameters call str2seconds;
- if any parameter corresponding formula is changed - create lambda for the evaluation formula, using multipliers or formula configured, and additionally a factor; 
- if maxtime specified - extend lambda with maxtime range;
- if rndtime specified - add it to lambda;