Import for EAT judgments

 Created a rake task & a model for it
 Updated .gitignore in order to ignore 'data' dir

Imported EAT jurisdiction_level1 table data
Imported EAT jurisdiction_level2 table data
Imported EAT level2jury table data
Added EAT judgment_jurisdictions table
 added the model relationships
 added a rake task for the whole 'import:eat'
Added Rails ERD diagraming gem
Added EAT causelist table
Removed duplicate instructions in README
Updated the README with EAT instructions
Added the Rake task to be used for EAT data import
Removed rails-erd gem added previously
Removed EAT's level2juri table
 And the related EatCategoryManager class
Implemented the 'import:eat:all' task correctly
Changed column type for EatCategories
Renamed EatCategoryHierarchy to EatCategoryDecision
Removed causelist table & related data
Delete the data for each EAT model
 Before insertion, purge all data
Fixed the model relationships
 Between EAT subcategory and EAT decision