chore(): Support Angular 7 without peer dependency warnings

package.json

@@ -30,11 +30,11 @@
   },
   "homepage": "https://github.com/angular/angularfire2#readme",
   "dependencies": {
-    "@angular/common": "^6.0.0",
-    "@angular/compiler": "^6.0.0",
-    "@angular/core": "^6.0.0",
-    "@angular/platform-browser": "^6.0.0",
-    "@angular/platform-browser-dynamic": "^6.0.0",
+    "@angular/common": ">=6.0.0 <8",
+    "@angular/compiler": ">=6.0.0 <8",
+    "@angular/core": ">=6.0.0 <8",
+    "@angular/platform-browser": ">=6.0.0 <8",
+    "@angular/platform-browser-dynamic": ">=6.0.0 <8",
     "firebase": "^5.5.0",
     "rxjs": "^6.0.0",
     "ws": "^3.3.2",
@@ -46,8 +46,9 @@
     "utf-8-validate": "~4.0.0"
   },
   "devDependencies": {
-    "@angular/compiler-cli": "^6.0.0",
-    "@angular/platform-server": "^6.0.0",
+    "@angular/compiler-cli": ">=6.0.0 <8",
+    "@angular/platform-server": ">=6.0.0 <8",
+    "@angular/animations": ">=6.0.0 <8",
     "@types/jasmine": "^2.5.36",
     "@types/request": "0.0.30",
     "concurrently": "^2.2.0",
@@ -82,7 +83,7 @@
     "systemjs": "^0.19.16",
     "systemjs-builder": "^0.15.7",
     "traceur": "0.0.96",
-    "typescript": ">=2.7.2 <2.8.0"
+    "typescript": ">=2.7.2 <2.8.0, >=3.1.1 <3.2"
   },
   "typings": "index.d.ts"
 }