Reorganize project tree
Fix. Assert functions return all parameters.
Fix. message explicitly convert to string.
Add. TEST_CASE function for compatibility with Lua 5.1/5.2
For example see test/selftest.lua.
```Lua
local _ENV = TEST_CASE"lunit.selftest.test1"
function test()...end
local _ENV = TEST_CASE"lunit.selftest.test2"
function test()...end
```
Fix. `begin` event does not call when use runner by default.
Merge pull request #5 from moteus/master

Assert functions return all parameters. Added TEST_CASE function for simpler compatibility with Lua 5.1/5.2. Assure there'a a runner for default run function. Move examples to separate directory. Thanks moteus!