[Code Style] Add JSHint rules

Add JSHint rules to complement allowing multiple var statements,
https://github.com/nasa/openmct/issues/142#issuecomment-212187972

[Code Style] Require one decl per var

[Code Style] Don't require separate var decls

...but allow them (for compatibility with existing code style)

[Code Style] Allow var decl after start of scope

[Code Style] Enforce codestyle during verify task

.jscsrc

@@ -1,3 +1,5 @@
 {
-    "preset": "crockford"
+    "preset": "crockford",
+    "requireMultipleVarDecl": false,
+    "requireVarDeclFirst": false
 }

.jshintrc

@@ -5,7 +5,7 @@
     "eqeqeq": true,
     "forin": true,
     "freeze": true,
-    "funcscope": true,
+    "funcscope": false,
     "futurehostile": true,
     "latedef": true,
     "noarg": true,
@@ -16,6 +16,7 @@
         "define",
         "Promise"
     ],
+    "shadow": "inner",
     "strict": "implied",
     "undef": true,
     "unused": "vars"

gulpfile.js

@@ -147,6 +147,6 @@ gulp.task('develop', ['serve', 'stylesheets', 'watch']);
 
 gulp.task('install', [ 'static', 'scripts' ]);
 
-gulp.task('verify', [ 'lint', 'test' ]);
+gulp.task('verify', [ 'lint', 'test', 'checkstyle' ]);
 
 gulp.task('build', [ 'verify', 'install' ]);