Update to Grails 2 and Release Plugin 2.0.4.

These are required in order to publish to the new central plugin repository.
Fix to get plugin working with Grails 2.2.

Groovy 2, which comes bundled with Grails 2.2, no longer has the
`GroovyShell.evaluate(InputStream)` method. As this was being used by
`FixtureFileLoader` the plugin would not compile.

We use a `Reader` instead of an `InputStream`, specifying the file
encoding based on a new `plugin.fixtures.file.encoding` configuration
option. The default is UTF-8.
Update change log.
Avoid cache provider warning when running integration tests.
Allow arbitrary nesting of fixture data via maps.

When dealing with one-to-many relationships, it's useful to specify the data
in a nested fashion. This change allows nesting of maps to any depth in order
to set up one-to-many data. For example,

    niall(Author, name: "Niall Ferguson", books: [
        [ title: "Colossus", labels: [
            [ name: "non-fiction" ],
            [ name: "starred" ] ],
        [ title: "Empire" ] ])

where Author 1---* Book 1---* Label.
Update docs for 1.2 release with new nesting syntax.
Update plugin version to 1.2 ready for release.
Add missing plugin metadata.
Allow parameters to be passed to named fixtures

This allows creating complex object graphs but overriding specific details if so desired.
Creates a bound variable called "params" in all fixtures loaded from a fixture file. If
the file was loaded without any parameters, the params object wil be an empty map.
Enable access to params inside build block

Previously the getProperty method in FixtureBuilder was interfering
Don't pass params around since it's on the fixture now
Give exceptions a serialVersionUID

When running tests in an IDE, these exceptions don't get serialized correctly when
loading fixtures using the remote-control plugin, as the classes get generated
slightly differently by grails and the IDE.
Add helper method to convert a Fixture into a Map

This allows easy passing of fixture-created data back to a calling test.
Fix NPE when sessionFactory isn't injected
Add comment explaining sessionFactory may be null.
Document new toMap() method.
Replace spaces with tabs for indent.
Merge branch 'remote-control'
Replace spaces with tabs for indent.
Merge branch 'parameters'

Conflicts:
	src/groovy/grails/plugin/fixtures/Fixture.groovy