implemented mock crypto repository

changed Cupertino search bar to Material UI 3
changed baseline color and card colors
implemented fetching crypto data from public API (untested)

lib/components/locale/l10n/app_localizations.dart

@@ -98,7 +98,7 @@ abstract class AppLocale {
   /// No description provided for @appBarTitle.
   ///
   /// In ru, this message translates to:
-  /// **'Криптобиржа'**
+  /// **'Персонажи из Гарри Поттера'**
   String get appBarTitle;
 
   /// No description provided for @search.

lib/components/locale/l10n/app_localizations_en.dart

@@ -7,7 +7,7 @@ class AppLocaleEn extends AppLocale {
   AppLocaleEn([String locale = 'en']) : super(locale);
 
   @override
-  String get appBarTitle => 'Crypto Exchange';
+  String get appBarTitle => 'Harry Potter characters';
 
   @override
   String get search => 'Search';

lib/components/locale/l10n/app_localizations_ru.dart

@@ -7,7 +7,7 @@ class AppLocaleRu extends AppLocale {
   AppLocaleRu([String locale = 'ru']) : super(locale);
 
   @override
-  String get appBarTitle => 'Криптобиржа';
+  String get appBarTitle => 'Персонажи из Гарри Поттера';
 
   @override
   String get search => 'Поиск';