[PATCH] fixture_scenarios_with_scenario_builder fixes

There are a few issues with fixture_scenarios_with_scenario_builder:

1. nested scenarios built in ruby can contain conflicting yaml labels

2. yaml files begin with ---, so when multiple are concat together everything after the second --- is ignored by yaml

3. if we workaround the --- issue by manually removing them, there is a second issue: (assuming we havent been bitten by #1 Add get_multi to cache_fu and all yaml labels are uniq) the yaml gets loaded into a hash, which is not ok for preserving order. this would make nesting suspect at best.

4. it was my experience that you can not modify an existing record in a nested scenario, only add new records (Mysql::Error: Duplicate entry exception)

Here are my additions:

1. Make inferred_record_name fallback much more unique, with a preference for primary_key if using the default "id", otherwise the sequence number

2. Load yaml fixtures into the database on a per file basis instead of concating everything and doing one pass. This preserves order of nesting and name scoping issues.

2a. #load_fixtures_from_yaml abstracts the fixture loading part

3. Added #insert_fixtures override which now will attempt to remove a record and retry if it gets an exception while inserting. limited to 1 retry, otherwise reraises the error

Please contact me to discuss if there are any questions.

Pastie patch:

http://pastie.caboo.se/77262

Also, thanks for this branch of the fixture_scenarios plugin. Nesting is what I was looking for when I found it!