added webpack-encore for managing frontend assets #113 (#122)

* updated installation docu #113
* rewritten login page #113
* added icheck plugin #113
* changed to YesNoType in edit forms #113
* updated CONTRIBUTING.md #113
* added start of developer docu #113
* added compile scripts and compiled assets #113

symfony.lock

@@ -362,6 +362,15 @@
     "symfony/orm-pack": {
         "version": "v1.0.5"
     },
+    "symfony/phpunit-bridge": {
+        "version": "3.3",
+        "recipe": {
+            "repo": "github.com/symfony/recipes",
+            "branch": "master",
+            "version": "3.3",
+            "ref": "179470cb6492db92dffee208cfdb436f175c93b4"
+        }
+    },
     "symfony/polyfill-intl-icu": {
         "version": "v1.6.0"
     },
@@ -461,6 +470,15 @@
             "ref": "c72d107d077f1654428edaed69415d0228c1aefe"
         }
     },
+    "symfony/webpack-encore-pack": {
+        "version": "1.0",
+        "recipe": {
+            "repo": "github.com/symfony/recipes",
+            "branch": "master",
+            "version": "1.0",
+            "ref": "a2f276eff6e95ca94be135d2d3e5c1247c6f8807"
+        }
+    },
     "symfony/yaml": {
         "version": "v4.0.3"
     },