#2900 HAPI dialog cleanup needed

[Jeremy Faden]

The HAPI Data Source Editor dialog needs some clean up.

1. there are excessive actions happening as the filter is changed, even though there are no updates to the datasets list
2. ico files are loaded each time the editor is entered, which is excessive and really a violation of the scientist's privacy. These should be limited to once per hour.
3. both the datasets filter and the parameters filter use the same "recents" list, which is incorrect.
4. There's a regression test in VATesting which should happen in nightly tests.

[Jeremy Faden]

(item 1) is done.
(item 3) is done. The scientists will loose any history they had, but I think this is acceptable.

[Jeremy Faden]

(item 2) is done.
(item 4) is done.