Rename/add configuration file options

In previous versions of repmgr, some options had ambiguous meanings,
and/or were used for slightly different purposes. This way we end
up with a couple more options (most of which probably won't need
adjusting) but greater clarity and flexibility.

Removed:

  master_reponse_timeout:
    renamed to "async_query_timeout", as this was its main usage

  retry_promote_interval_secs:
    replaced by "primary_notification_timeout"

Added:
  async_query_timeout:
    timeout (in seconds) when executing asynchronous queries

  primary_notification_timeout:
    number of seconds to wait for notification from the new primary
    after a failover

  primary_follow_timeout:
    number of seconds to wait for the new primary to become available
    when executing "repmgr standby follow"

repmgr.h

@@ -43,6 +43,9 @@
 #define DEFAULT_RECONNECTION_ATTEMPTS    6
 #define DEFAULT_RECONNECTION_INTERVAL    10
 #define DEFAULT_STATS_REPORTING_INTERVAL 2
+#define DEFAULT_ASYNC_QUERY_TIMEOUT      60
+#define DEFAULT_PRIMARY_NOTIFICATION_TIMEOUT 60
+#define DEFAULT_PRIMARY_FOLLOW_TIMEOUT 60
 
 #define FAILOVER_NODES_MAX_CHECK 50