Testsuite: Replace --version=x.y.z with package@x.y.z

testsuite: Use built dub, not system one in more tests ...

Some places were missed during the last fixups.

Testsuite: Fix calls to die to always include line numbers ...

'die' actually taking two parameters seems to be a little-known fact.

Make 'dub remove' remove all packages by default in non-interactive mode ...

Given how often it is used in the test-suite, it should be self-obvious
that it will be what most users want.

Fix some tests that were using installed DUB instead of built ones ...

Those tests were not actually testing the built dub,
but whatever was installed on the machine (or in the path) instead.

Use a value < ushort.max for tests using the test_registry ...

It is possible for the PID to be >= 65536, in which case the dub_registry
would fail to parse the argument and error out.
This can be frequently experienced on long running systems,
for example Mac OSX.

Fix #1412 - wait longer until Vibe.d has started

Fix test/fetchzip.sh

Use echo instead of bash here string

fetchzip.sh: Display $retryCount in the error log output

dump dub output on failure

test fallback mirror usage on server errors

fix retry on http status error ...

- silent http status errors (e.g. 502) should be responsible
  for most "corrupted" zip packages

more robust testing ...

- require arguments for test_registry
- check removal of broken package

Don't break out of the retry loop for ZipExceptions - fixes #1336