New feature: support of regex in pattern check

[tpoindessous]

Hi

we use beeping with pattern check and we would like to use regex pattern.

For example, we check Hashicorp Vault via an API call and we need to verify that multiple parameter are set.

For example, we call Vault on this URL ( https://vault/v1/sys/health ) and we get this response :

{"initialized":true,"sealed":false,"standby":false,"server_time_utc":1505381889,"version":"0.6.2","cluster_name":"vault-cluster-YYYYYY","cluster_id":"XXXXXX"}

We would like to use this regexp : .*\"sealed\":\"false\".*\"cluster_name\":\"vault-cluster.*

Thanks !