Replace with `be true` and `be false` and make predicate return a
boolean.

> Methods that don't return a boolean, shouldn't end in a question mark.
-- https://github.com/bbatsov/ruby-style-guide#naming

The section name appears on a line by itself, in square brackets (`[` and
`]`), all characters between the opening `[` and the closing `]` should
be considered to form the section name.

…ction-names

This should fix the build.

If this change isn't desired,
./spec/unit/puppet/provider/ini_setting/ruby_spec.rb:1044 could be
changed to:

```ruby
provider.exists?.should be_nil
```

Verifying that this PR addresses #98

…rks-in-section-names

Ini_file module does not recognize section names with forward slashes in them

https://tickets.puppetlabs.com/browse/MODULES-1194