Upgrade Docker dev environment

Author: cyberhobo

composer.json

@@ -14,12 +14,7 @@
 		{
 			"type": "vcs",
 			"url": "https://github.com/vernal-creative/html-to-markdown"
-		},
-		{
-			"type": "vcs",
-			"url": "https://github.com/Freemius/wordpress-sdk"
 		}
-
 	],
 	"autoload": {
 		"classmap": ["admin/", "core/", "interfaces/", "enums/" ]
@@ -33,15 +28,15 @@
 		"scribu/scb-framework": "dev-replyable",
 		"vernal-creative/html-to-markdown": "dev-postmatic",
 		"calderawp/caldera-modals" : "1.0.1",
-		"xamin/handlebars.php": "dev-php-52",
+		"salesforce/handlebars-php": "^2.3.0",
 		"freemius/wordpress-sdk": "^2.4.1",
 		"postmatic/commentium": "^1.0.3"
 	},
 	"require-dev": {
 		"roave/security-advisories": "dev-master",
-		"phing/phing": "2.8.*",
-		"phpunit/phpunit": "4.2.*",
-		"tedivm/jshrink": "1.0.*",
+		"phing/phing": "2.16.*",
+		"phpunit/phpunit": "5.7.27",
+		"tedivm/jshrink": "1.3.*",
 		"rosio/wordpress-i18n-tools": "dev-master"
 	},
 	"scripts": {