Added parsing plurals into the JSON

[jdegroot-aa]

I've added some functionality to parse string plurals into the resulting JSON. Additionally, I've updated the apktool dependency to 2.2.2 and made source and target Java versions Java 1.8.

Example:

<plurals name="CarsQuantity>
    <item quantity="few">cars</item>
    <item quantity="many">cars</item>
    <item quantity="one">car</item>
    <item quantity="other">cars</item>
    <item quantity="two">cars</item>
    <item quantity="zero">cars</item>
</plurals>

Parses into:

"CarsQuantity" : {
    "other" : "cars",
    "zero" : "cars",
    "one" : "car",
    "two" : "cars",
    "few" : "cars",
    "many" : "cars"
  }

[jsf-clabot]

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