Created ActiveRecord::Tasks::SQLServerDatabaseTasks class

which addresses compatibility issues with Rails v4.1.8.

This is not yet a complete implementation of the ActiveRecord::Tasks
interface.

Adds test cases in test/cases/tasks/sqlserver_rake_test_sqlserver.rb

requires the new sqlserver_database_tasks from
lib/activerecord-sqlserver-adapter.rb

Updates to test/cases/(associations_test_sqlserver &
resolver_test_sqlserver) to address failing tests.

Added tags to .gitignore so ctags index files won't be checked in.

Fixed typo in RUNNING_UNIT_TESTS.md.