Compile examples in continuous integration, update example_3 readme

Altered the rake build so that it passes. The example_3 shows off
some failing tests, so the rake build has to ignore those.
Update .gitignore file with executables from examples

.travis.yml

@@ -15,6 +15,10 @@ install: gem install rspec
 script:
   - cd test && rake ci
   - make -s
+  - make -s DEBUG=-m32
   - cd ../extras/fixture/test && rake ci
   - make -s default noStdlibMalloc
   - make -s C89
+  - cd ../../../examples/example_1 && make -s
+  - cd ../example_2 && make -s
+  - cd ../example_3 && rake