Add sample ruby-version file.

Also adds some helpful stuff to gitignore.

This is in the spirit of helping beginners, since I think this project
is meant to be very beginner-friendly.
some refactorings to reduce code complexity
starting extracting constant strings into config/initializers/strings.rb and some more refactoring of organizations controller to get the search method shorter and cleaner
Add new value object to contain CSV column header names
Refactor: Add an attribute reader for the headers hash inside CSVHeader
Remove @@column_mappings from the constructor argument list for CreateOrganizationFromArray
Refactor: Remove duplication between Organization.import_category_mappings and Organization.import_addresses
Merge pull request #100 from cored/extract-csv-header-value-object

Extract csv header value object
Merge pull request #101 from cored/remove-duplication-between-category-mappings-import-address

Refactor: Remove duplication
Merge pull request #98 from manzoid/add-ruby-version-sample

Add sample ruby-version file.
red cucumber for email import operation
adding email test csv to gitignore
first pass on import emails for orgs - no sad path included - should refactor file exists step to be neater regarding header row
Merge pull request #102 from tansaku/develop

First go at an email import feature that would take a list of emails and associate with existing organizations