add ruby 2.6.0 into travis (#178)

* add ruby 2.6.0 into travis

* update rubocop

* disable Layout/RescueEnsureAlignment

Author: KazuCocoa

.rubocop.yml

@@ -32,3 +32,5 @@ Naming/AccessorMethodName:
   Enabled: false
 Naming/MemoizedInstanceVariableName:
   Enabled: false
+Layout/RescueEnsureAlignment:
+  Enabled: false

.travis.yml

@@ -6,7 +6,7 @@ rvm:
   - 2.3
   - 2.4
   - 2.5
-#  - 2.6
+  - 2.6
 
 before_install:
   - gem update bundler

appium_lib_core.gemspec

@@ -31,7 +31,7 @@ Gem::Specification.new do |spec|
   spec.add_development_dependency 'minitest', '~> 5.0'
   spec.add_development_dependency 'minitest-reporters', '~> 1.1'
   spec.add_development_dependency 'webmock', '~> 3.4.0'
-  spec.add_development_dependency 'rubocop', '0.60.0'
+  spec.add_development_dependency 'rubocop', '0.61.0'
   spec.add_development_dependency 'appium_thor', '~> 1.0'
   spec.add_development_dependency 'pry'
   spec.add_development_dependency 'pry-byebug'