Fix #131. Permit quoted variable identifiers in 'with' map
Allowing strings to be used as keys in maps
Removed unnecessary method
Supporting different types of template location:

- File
- Classpath
- Web Resource

Removed all usages of java.io.File to get the relative paths (only using it for files).
Added unit tests to check for the FilePath behaviour.
Merge pull request #1 from lyncodev/string-map-keys

String map keys
Merge pull request #132 from thomas-p-wilson/with-variable-quoting

Fix #131. Permit quoted variable identifiers in 'with' map
Merge pull request #135 from lyncodev/classpath-in-jtwig-view-resolver

Supporting different types of template location