Fixed syntax issues

SyntaxError
-----------
/usr/lib64/ruby/gems/1.8/gems/zabbixapi-0.5.7/lib/zabbixapi/2.0/classes/triggers.rb:42: invalid regular expression; there's no previous pattern, to which '{' would define cardinality at 1: /{(\d*)}/
/usr/lib64/ruby/gems/1.8/gems/zabbixapi-0.5.7/lib/zabbixapi/2.0/classes/triggers.rb:47: invalid regular expression; there's no previous pattern, to which '{' would define cardinality at 1: /{.*\:/