Add support for @PathVariable annotation in ManagedService

This pull request adds support for Spring-like, albeit more limited, handling of PathVariables in Managed Service. The proposed use is to treat placeholders in path passed to ManagedService annotation, for example `@ManagedService(path = "/pathVar/{a}/pathTest/{b}")`, as names of variables which will get values of those path elements. In the class code the variable should be annotated:
```
@PathVariable
private String a;
```
or, if the name is different than path component placeholder, the placeholder can be specified in the annotation (`@PathVariable("b")`).

The parsing is quite simple, so the components have to be separated with slashes, and the number of slashes in pattern and real path should be equal.
No action is performed if no annotation is present.