Bump version to 1.8.0.

Author: jimmycuadra

lita-slack.gemspec

@@ -1,6 +1,6 @@
 Gem::Specification.new do |spec|
   spec.name          = "lita-slack"
-  spec.version       = "1.7.2"
+  spec.version       = "1.8.0"
   spec.authors       = ["Ken J.", "Jimmy Cuadra"]
   spec.email         = ["[email protected]", "[email protected]"]
   spec.description   = %q{Lita adapter for Slack.}
@@ -17,7 +17,7 @@ Gem::Specification.new do |spec|
   spec.add_runtime_dependency "eventmachine"
   spec.add_runtime_dependency "faraday"
   spec.add_runtime_dependency "faye-websocket", ">= 0.8.0"
-  spec.add_runtime_dependency "lita", ">= 4.7.0"
+  spec.add_runtime_dependency "lita", ">= 4.7.1"
   spec.add_runtime_dependency "multi_json"
 
   spec.add_development_dependency "bundler", "~> 1.3"