Revert "Added rudimentary system environment variable support. (#284)" (#470)

This reverts commit 7a8fd62535.

android/dotenv.gradle

@@ -50,7 +50,7 @@ def loadDotEnv(flavor = getCurrentFlavor()) {
         f.eachLine { line ->
             def matcher = (line =~ /^\s*(?:export\s+|)([\w\d\.\-_]+)\s*=\s*['"]?(.*?)?['"]?\s*$/)
             if (matcher.getCount() == 1 && matcher[0].size() == 3) {
-                env.put(matcher[0][1], System.env[matcher[0][1]] || matcher[0][2].replace('"', '\\"'))
+                env.put(matcher[0][1], matcher[0][2].replace('"', '\\"'))
             }
         }
     } else {

ios/ReactNativeConfig/ReactNativeConfig.m

@@ -8,8 +8,6 @@
 }
 
 + (NSString *)envFor: (NSString *)key {
-    NSString *envValue = (NSString *)[[[NSProcessInfo processInfo]environment]objectForKey:key];
-    if (envValue) return envValue;
     NSString *value = (NSString *)[self.env objectForKey:key];
     return value;
 }