houndci suggested fixes.

Author: peterkovacs

lib/bitbucket_rest_api.rb

@@ -77,7 +77,7 @@ def lookup_constant(const_name)
                :Issues          => 'issues',
                :User            => 'user',
                :Users           => 'users',
-               :Invitations      => 'invitations'
+               :Invitations     => 'invitations'
 
   #:Teams           => 'teams',
   #:PullRequests    => 'pull_requests',

lib/bitbucket_rest_api/client.rb

@@ -51,9 +51,8 @@ def user_api(options = {})
       @user_api ||= ApiFactory.new 'User', options
     end
 
-    def invitations( options = {} )
-      @invitations ||= ApiFactory.new 'Invitations', options
+    def invitations(options = {})
+      @invitations ||= ApiFactory.new "Invitations", options
     end
-
   end # Client
 end # BitBucket

lib/bitbucket_rest_api/invitations.rb

@@ -2,13 +2,14 @@
 
 module BitBucket
   class Invitations < API
-    def invite( user_name, repo_name, emailaddress, perm )
+    def invite(user_name, repo_name, emailaddress, perm)
       _update_user_repo_params(user_name, repo_name)
       _validate_user_repo_params(user, repo) unless user? && repo?
       _validate_presence_of emailaddress
-      perm ||= 'write'
+      perm ||= "write"
 
-      post_request( "/invitations/#{user}/#{repo.downcase}/#{emailaddress}", permission: perm )
+      post_request("/invitations/#{user}/#{repo.downcase}/#{emailaddress}",
+                   permission: perm)
     end
   end
 end