Add dependency json output to file for use with installer/launcher

[gabizou]

Pretty basic usage of the dependencies needed, outputs a manual built json file (since I couldn't for the life of me get the buildscript to import something like gson or jackson etc.)

This can be tested with ./gradlew emitDependencies

The output will look like

{
 "dependencies":
  [
    {
      "group": "org.spongepowered",
      "module": "mixin",
      "version": "0.8.1-SNAPSHOT",
      "md5": "4ba6337b3724c7d107ad217"
    },
    {
      "group": "org.ow2.asm",
      "module": "asm-util",
      "version": "6.2",
      "md5": "f102f32ccf7fa2d7b2a751c4"
    },
    {
      "group": "com.google.guava",
      "module": "guava",
      "version": "21.0",
      "md5": "d91f850a617791ab5d4e4d1f6"
    },
    {
      "group": "org.spongepowered",
      "module": "plugin-spi",
      "version": "0.1.3-SNAPSHOT",
      "md5": "025d7261b54104c6bbfa5145"
    },
    {
      "group": "javax.inject",
      "module": "javax.inject",
      "version": "1",
      "md5": "280754b0ee7469153631d2e"
    },
    {
      "group": "org.apache.logging.log4j",
      "module": "log4j-api",
      "version": "2.11.2",
      "md5": "3f7e51e3d030d79a090243d"
    },
    {
      "group": "org.apache.logging.log4j",
      "module": "log4j-core",
      "version": "2.11.2",
      "md5": "8db5c5aa07a3db57d01c266"
    },
    {
      "group": "com.zaxxer",
      "module": "HikariCP",
      "version": "2.6.3",
      "md5": "c3f015f12eb7b50e53ae"
    },
    {
      "group": "org.apache.logging.log4j",
      "module": "log4j-slf4j-impl",
      "version": "2.11.2",
      "md5": "362e4c465c99f41154d8"
    },
    {
      "group": "org.spongepowered",
      "module": "configurate-core",
      "version": "3.7.1",
      "md5": "152b2b316e022328acc2b36e7"
    },
    {
      "group": "org.spongepowered",
      "module": "configurate-hocon",
      "version": "3.7.1",
      "md5": "478b29e0c473925801629"
    },
    {
      "group": "org.spongepowered",
      "module": "configurate-json",
      "version": "3.7.1",
      "md5": "b29803563b1091227155802"
    },
    {
      "group": "org.cadixdev",
      "module": "lorenz",
      "version": "0.6.0-SNAPSHOT",
      "md5": "c680f3a52a44587a56547b1a"
    },
    {
      "group": "org.cadixdev",
      "module": "atlas",
      "version": "0.3.0-SNAPSHOT",
      "md5": "2b19057ae14359a87672b414ca"
    },
    {
      "group": "cpw.mods",
      "module": "modlauncher",
      "version": "4.1.0",
      "md5": "56e665167083946b16736237"
    },
    {
      "group": "cpw.mods",
      "module": "grossjava9hacks",
      "version": "1.1.0",
      "md5": "1ad27730734a786f461e0484400"
    },
    {
      "group": "net.minecraftforge",
      "module": "accesstransformers",
      "version": "1.0.5",
      "md5": "c7707320fe71e36556e2"
    },
    {
      "group": "org.ow2.asm",
      "module": "asm-commons",
      "version": "7.1",
      "md5": "53524b59255e482e0aa285"
    },
    {
      "group": "org.ow2.asm",
      "module": "asm-tree",
      "version": "7.1",
      "md5": "e019fe1e642e122b52f58d74b"
    }
  ]
}

``