set brooklyn properties in mgmt context *before* starting dependent managers
use `Os.tmp()` when we create temp dirs and files, and simplify creation and deletion, defaulting to delete on exit etc, use LocalManagementContextForTests in more places, and other misc test tidies
add support for keystore set from brooklyn.properties
correct logic for when different webapp explicitly specified via launcher `webapp(...)`
code review comments: clean up checkSafe and add some comments
more info and "eventually" check, for test failure
Merge pull request #1466 from ahgittin/certs-and-temp

Keystore can be specified from brooklyn.properties, and tidies to use of temp dir and tidies in tests