Remove all GUI files and references to the GUI

As the NodeJS dependency no longer exists, the archive script has
been replaced with a CPack implementation, and the
set_version_number script turned into a Python script.

scripts/travis/loot-api.bintray.json

@@ -8,7 +8,7 @@
     "name": "REPLACE_THIS_VERSION"
   },
   "files": [{
-    "includePattern": "build/(loot-api_.+\\.tar.xz)",
+    "includePattern": "build/package/(loot_api-.+\\.tar.xz)",
     "uploadPattern": "$1"
   }],
   "publish": true

scripts/travis/loot.bintray.json

@@ -1,15 +0,0 @@
-{
-  "package": {
-    "name": "loot",
-    "repo": "loot",
-    "subject": "wrinklyninja"
-  },
-  "version": {
-    "name": "REPLACE_THIS_VERSION"
-  },
-  "files": [{
-    "includePattern": "build/(loot_.+\\.tar.xz)",
-    "uploadPattern": "$1"
-  }],
-  "publish": true
-}