v0.4.0: Support packaging of lambda layers

Notable Changes

• #38 - Support the packaging of AWS lambda layers. Big feature of the day!

• Update documentation and include an example on how a developer can package both lambda functions and layers (juniper/tree/master/examples/fondolayers).

• Manifest file has also been updated to support a new section where the layers will be defined.

v0.2.6: Fix yaml.load warning (#33)

Used safe_load which limits the ability to construct an arbitrary Python object to simple Python objects like integers or lists.