DryRun and Baseline implementation for RH

Hi.
I have implemented baseline and dry-run for RH, based on your MockDatabase implementation skeleton.

However, I've re factored it into 3 separate classes:
 * DatabaseDecoratorBase - proxy to proxied database implementation with required methods marked as virtual
 * DatabaseBaselineDecorator - ignores everything, except script insertion
 * DatabaseDryRunDecorator - ignores everything

There is some bugs and exceptions happening when --dryrun or --baseline are used on a non-existing database, however proper implementation of those do require changes in core Database class, which I haven't done yet. 

Also, it seems that integration tests were using incorrect path to SQL scripts folder, I've fixed that as well at https://github.com/kolupaev/roundhouse/commit/b96de52127c8b323fcc4cedc50ecab2954d39af6.

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Best regards, 
Val