Fix runing client tests on CI server

[atimin]

Closes #45

[atimin]

I've embedded the demo server into Ttravis script and it's working well on my machine. But it seems that some tests aren't stable and can't pass in Travis'es environment. @huebl , could you check them?

[huebl]

Hi @FLIPBack, I look at the problem.

[huebl]

The crashes are very rare in a local environment. Only every 10 to 20 times.

I found an error in the synchronization when closing the connection. After the fix but still more crashes have occurred. My suspicion: Bug #10 still needs to be fixed. The crashes look at least very similar.

[atimin]

Hi, @huebl
I suggest merging this PR into Release 3. Then we reopen #10 and make a new PR to fix it. I advise you to mark your PR or commit with "close(fix) #issue" so that we can see if the bug is fixed in current branch. I tried to find where #10 is closed but didn't manage.