how to use SQL to convert string-delimited arrays

closes #60
Merge pull request #66 from turadg/patch-1

how to use SQL to convert string-delimited arrays
Array contains operator ( @> ) support

1. Add support for the Postgres array contains operator. This operator
is like overlap, but expects all of the provided elements to be in the
array.

    MyModel.where.array_contains(tags: [1, 2])

2. Moved the array nodes into their own file
Update querying doc to include array_contains
Remove explicit array_contains where extension, use contains instead

Removed the array_contains where extension and changed the existing
contains extension to check the type of the column. It will use either
array_contains or the INET contains depending on whether the column is
an array or not.
Merge pull request #67 from jagregory/array_contains

Array contains operator support
Renames Arel array_overlap to overlap
Removes array_contains in favor of a column aware contains
Replaced .symbolize with .to_sym in arel nodes.

Without this patch the arel node classes ContainedWithinEquals and
ContainsEquals used .symbolize instead of .to_sym to crate the
operators. This causes a NoMethodError with: undefined method
`symbolize' for "<<=":String.
This patch addresses this issue by using to_sym instead of
symbolize.
Merge pull request #70 from omcnet/fix-arel-node-operators

Replaced .symbolize with .to_sym in arel nodes.
Closes #69

Empty strings are converted to nil by string_to_cidr_address
Cleaning up specs
Changes using syntax, updates specs
Adds support to create indexes concurrently
Docs and changelog update, and version bump

[ci skip]
Add EAN13 data type support via isn extension

This commit is my first attempt at integrating the isn extension with
postgres_ext. I added EAN13 first because it is the superset of the
other included types. The style, structure, and syntax are mostly
parroted from postgres_ext's existing data types. As such, there are a
few extraneous (green) specs as well as room for optimization and
improvement.
Merge pull request #73 from ezkl/add-isn-support

ISN Data Types
Fixes 2d array parsing

Fixes #75 by correcting item_to_string to only escape values if
the casted_value and original value are both strings
Adds spec for setting int arrays
Fixed compatibility with Squeel