Ensure table prefix/suffix are not in schema.rb

Without this patch, when a table prefix or suffix is
defined, it will appear in the schema.rb for the
add_foreign_key statements.
Truncates the schema_migrations index

Problem
--------
Assuming the following:
```ruby
ActiveRecord::Base.table_name_prefix = 'toolong_'
```

When `db:migrate` is run, the index assigned by `ActiveRecord` is too
long.
```
-- initialize_schema_migrations_table()
rake aborted!
Index name 'toolong_unique_schema_migrations' on table
'toolong_schema_migrations' is too long; the limit is 30 characters
```

This issue is present in rails/rails on branches `2-3-stable` through
`3-2-stable`. In the latest `master`, the code has changed, but the
issue still exists and should be resolved by this code.

Here's where it is implemented in `3-2-stable`:
https://github.com/rails/rails/blob/3-2-stable/activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb#L429

Solution
---------
The fix for this is to provide a method that supports a shorter index
name when the schema_migrations table is initialized.
Merge pull request #282 from reenhanced/nh-no-foreign-keys-in-schema-dump

Ensure table prefix/suffix are not in schema.rb
Merge pull request #276 from reenhanced/nh-migration-index-truncate

Truncates the schema_migrations index
using File::PATH_SEPARATOR to split paths

Conflicts:

	lib/active_record/connection_adapters/oracle_enhanced_jdbc_connection.rb
Revert "Merge pull request #282 from reenhanced/nh-no-foreign-keys-in-schema-dump"

This reverts commit 5eac0119592c3d9c40b0b3ff00536686727e13f8, reversing
changes made to 33d8be0d8ccbe6ab5feedd2748efe458c5c03cf5.
Change Gemfile to support Rails 3.2