INT-2868 Fix SSL Key Store Resource Handling

Documentation indicates that the keystore and truststore
arguments can be resource patterns (file:..., classpath:..., etc)
but the code always used a ClasspathResource.

Use a PathMatchingResourcePatternResolver to interpret the
pattern correctly.

Add tests.
Merge pull request #697 from garyrussell/INT-2868

* garyrussell-INT-2868:
  INT-2868 Fix SSL Key Store Resource Handling