Fixes for the Stash library

[legal90]

1. Default settings should not be specified in attribute files

Chef::Recipe::Stash.settings method is going to set default settings:

settings ||= node['stash']
settings['database']['port'] ||= default_database_port settings['database']['type']
settings['database']['testInterval'] ||= 2

But it will never be done because the node will always have these attributes specified in attributes/default.rb.
For example, even if we set ['database']['type'] = 'postgresql', the port will be "3306" anyway. So that, these attributes should not be specified in attribute file.

2. default_database_port method is unavailable

This method should be a class method, instead of an instance method. Otherwise, it can not be called from Chef::Recipe::Stash.settings method

3. settings should be a hash.

While copying settings ||= node['stash'] it should be also converted to Hash object, becouse Node object is read-only and overriding below will be unavailable.

[legal90]

@bflad, Please, check this out.
The Travis build failure is caused by updated Rubocop policies and is not related to this PR directly.

[legal90]

I've just improved the definition of Stash settings in library/stash.rb:
Now default settings can be defined by node attributes and some of them can be overwritten by values from data bag.

[legal90]

I've fixed some issues by applying the deep merge to hashes. Now it is working fine, look at the example below.
Let's assume, that node has the following attributes:

# Attributes
node.set['stash']['database']['host']     = 'localhost'
node.set['stash']['database']['name']     = 'stash'
node.set['stash']['database']['password'] = 'changeit'
node.set['stash']['database']['user']     = 'stash'
...
node.set['stash']['jvm']['minimum_memory']  = '512m'
node.set['stash']['jvm']['maximum_memory']  = '768m'

At the same time there is a stash data bag containing the following settings:

# Data bag
{
  "id": "stash",
  "test": {
    "database": {
      "user": "overridden_user",
      "password": "overridden_password"
    },
    "jvm": {
      "maximum_memory": "2048m"
    }
  }
}

In the result values from attributes will be overridden by settings from the data bag:

# Result settings:
settings['database']['host']     == 'localhost'
settings['database']['name']     == 'stash'
settings['database']['password'] == 'overridden_password'
settings['database']['user']     == 'overridden_user'
...
settings['jvm']['minimum_memory']  = '512m'
settings['jvm']['maximum_memory']  = '2048m'

[bflad]

@legal90 this is an excellent improvement - thanks! Sorry it took me so long to get this in here. I double checked the README documentation and it already mentions the override behavior which this actually makes work as expected.

[bflad]

Will release in 3.13.0