[REFACTOR] change variable names into camelCase

lib/config/strings.dart

 // Frequently used strings are stored here
 // No hardcoding string view files. Store here.
 
-final String DEV_BASE_URL = "poipole.herokuapp.com";
-final String BASE_URL = "poipole.herokuapp.com";
-String KEY = "";
-String CSRF = "";
-String SESSION_ID = "";
+final String devBaseUrl = "poipole.herokuapp.com"; 
+final String baseUrl = "poipole.herokuapp.com";
+String key = "";
+String csrf = "";
+String sessionId = "";
 
 setKey(String key) {
-  KEY = key;
+  key = key;
 }
 
 setSessionId(String sessionId) {
-  SESSION_ID = sessionId;
+  sessionId = sessionId;
 }
\ No newline at end of file

lib/flavor/flavor.dart

@@ -7,9 +7,9 @@ class ApiFlavor {
 
   static String getBaseUrl() {
     if (ApiFlavor.flavor == BuildFlavor.development.toString()) {
-      return DEV_BASE_URL;
+      return devBaseUrl;
     } else {
-      return BASE_URL;
+      return baseUrl;
     }
   }