feat(package): relaxed peer dependencies to allow ng v4 (#713)

Add Angular 4 peer dependencies support

Author: smartm0use

package.json

@@ -45,8 +45,8 @@
   "homepage": "https://github.com/valor-software/ng2-file-upload#readme",
   "dependencies": {},
   "peerDependencies": {
-    "@angular/common": "^2.3.0",
-    "@angular/core": "^2.3.0"
+    "@angular/common": "^2.3.1 || >=4.0.0",
+    "@angular/core": "^2.3.1 || >=4.0.0"
   },
   "devDependencies": {
     "@angular/common": "2.4.3",