[resolver] get rid of CacheResolver::getBrowserPath method.
add ResolverInterface::isStored
add NotResolvableException
Merge pull request #3 from havvg/resolver-get-rid-of-get-browser-path

add ResolverInterface::isStored
[resolver][web-path] always return string on resolve.
update UPGRaDE.md
fix comments.
Merge pull request #284 from formapro-forks/resolver-get-rid-of-get-browser-path

[1.0][CacheResolver] Resolver get rid of get browser path