DataMapper auto_migrate/auto_upgrade the default repository

tasks in question:
* rake dm:auto:migrate
* rake dm:auto:upgrade
Added range_field_tag
closes #1276 if acceptable

defines:
```
	range_field_tag(name, options = {})
```
options are:
- name
- :min/:max
  - or :range

see PR + doc for formal definition.
Merged range_field_tag.* templates into form_tag.* should be the correct place
Changed range option parsing to a simpler code
Merge pull request #1299 from Ortuna/range-input-helper

Added range_field_tag
Merge pull request #1298 from Ortuna/issue-1293

DataMapper auto_migrate/auto_upgrade the default repository