Fix readme nested webpage example

The readme's nested section provides some sample code that doesn't even compile. Fixing that and introducing a test class for such sample code.

What I don't like: No asserts in the test to keep the code as it is in the readme. 

Another issue: Calling test in sbt doesn't seem to run the CombinatorTests and AdvancedTests. Didn't have time to look into this. There are also two feature warnings. 

Here is the test report:

```shell
> test
[info] Compiling 4 Scala sources to /Users/ppurang/repositories/git/external/scala.rx/target/scala-2.10/test-classes...
[warn] there were 2 feature warnings; re-run with -feature for details
[warn] one warning found
Home Page! time: 1365504733425
Home Page! time: 1365504733428
About Me, time: 1365504733471
About Me, time: 1365504733474
[info] BasicTests:
[info] ReadmeTests:
[info] Nesting
[info] config tests
[info]   WebPage
[info] - name
[info] sig tests
[info]   basic
[info]   - signal Hello World
[info]   - long chain
[info]   - complex values inside Var[]s and Rx[]s
[info]   language features
[info]   - pattern matching
[info]   - implicit conversions
[info]   - use in by name parameters
[info] obs tests
[info] - obs Hello World
[info] - obs simple example
[info] - listening the multiple signals
[info] error handling
[info] - simple catch
[info] - long chain
[info] nested Rxs
[info] Passed: : Total 28, Failed 0, Errors 0, Passed 28, Skipped 0
[success] Total time: 11 s, completed Apr 9, 2013 12:52:16 PM
```