Try to deduce the name when removing an index

The migrator has enough information that a custom name should not need to be passed. However, if it would select the wrong index a custom name can still be provided.
Add back the explicit test for removing an index by name
Merge pull request #38 from erikogan/mismatched-indices

Try to deduce the name when removing an index
Update homepage url in gemspec
Fix rubygems source warnings
Update travis-ci links
Add ruby-version and ruby-gemset to gitignore
Add conditional migrations via filter.

This is part 1 of the WIP - the triggers still copy all new data and
updated data.
Not using conditional triggers with joins
Dont require arel
Change back the spec database params
Don't alias the change_table method
Have attribute reader, no need for method
Add rdoc to migrator for filter
Update readme
Remove old describe block
Bump version to 2.0.0 due to API change
Test against MRI 2.0.0 instead of 1.8.7

1.8.7 reached its End Of Life recently.
Correctly specify allow_failures
Mention MRI 2.0.0 issues in README