Change define_column -> Groonga::Schema

Allow a change of table definition
Support Array
Support "integer32"
Use Groonga::Schema::TableDefinition#column
create_table -> change_table
Support type: :vector
Support table.index
Merge branch 'feature/use-schema'
MiniTest::Unit::TestCase -> MiniTest::Test
test_grn_mini_array.rb -> test_array.rb