Fix #61 - Add list of blocked users to the UI; clean up failed push notifications API

Try to fix Travis CI setup

Gemfile.lock

@@ -147,9 +147,6 @@ GEM
     execjs (2.7.0)
     fabrication (2.15.2)
     fast_blank (1.0.0)
-    fcm (0.0.2)
-      httparty
-      json
     font-awesome-rails (4.6.3.1)
       railties (>= 3.2, < 5.1)
     fuubar (2.1.1)
@@ -183,8 +180,6 @@ GEM
       domain_name (~> 0.5)
     http-form_data (1.0.1)
     http_parser.rb (0.6.0)
-    httparty (0.14.0)
-      multi_xml (>= 0.5.2)
     httplog (0.3.2)
       colorize
     i18n (0.7.0)
@@ -232,7 +227,6 @@ GEM
     mini_portile2 (2.1.0)
     minitest (5.10.1)
     multi_json (1.12.1)
-    multi_xml (0.6.0)
     net-scp (1.2.1)
       net-ssh (>= 2.6.5)
     net-ssh (4.0.1)
@@ -470,7 +464,6 @@ DEPENDENCIES
   dotenv-rails
   fabrication
   fast_blank
-  fcm
   font-awesome-rails
   fuubar
   goldfinger