add test code for irteus/demo into irteus-demo.l and remove direct writi...

Add test code for irteus/demo into irteus-demo.l and remove direct writing of test lines in .travis.yml according to discussion in https://github.com/euslisp/jskeus/commit/83432a3d75c950481e9f3079b077f47f73c1059d

The purpose of this PR is to enable to call `irteus/test/irteus-demo.l` directly.
After this commit, we can replace test lines in .travis.yml by `find test/ -iname "*.l" | xargs -n1 irteusgl` according to @k-okada suggestion. 
https://github.com/euslisp/jskeus/commit/83432a3d75c950481e9f3079b077f47f73c1059d

However, currently `irteus/test/unittest.l` cannot be called in .travis.yml 
because of invalid exit code[1] or testing of `intentional failure`[2].
After we can use `irteus/test/unittest.l`, 
I can create PR for  `find test/ -iname "*.l" | xargs -n1 irteusgl` .

[1] https://github.com/euslisp/EusLisp/pull/19
[2] https://github.com/jsk-ros-pkg/jsk_roseus/pull/21#issuecomment-42518691