Improve alert history

[alyan2008]

Currently I have more than 41000 alerts for the last 7 days and all those alerts display in one window. In result its very heavy tab, its very hard to scroll and find something. Browser just freezes.

[cryptoquick]

@jaredscheib Hey, we should make the pagination we're making for the Hosts page componentized enough to reuse for the Alerts page as well. Two birds with one stone.

[nhaugo]

@alyan2008 we will be integrating with the kapacitor alert api soon influxdata/kapacitor#829

Thus we are not likely to address this problem until then. The temporary workaround is to set the retention policy of the chronograf database so the older alerts start falling off.

https://docs.influxdata.com/influxdb/v0.9/query_language/database_management/#modify-retention-policies-with-alter-retention-policy

[nhaugo]

We are looking to work around this by limiting the range of time alerts are returned from. #1030