We found some SD card on Raspberry Pi could have very bad performance.
It could take seconds to save small amount of data.
If the DUT receives data and save it as log, then it stops receiving data until log is saved.
This could lead to expect timeout. As an workaround to this issue,
``BaseDUT`` class will create a thread to save logs.
Then data will be passed to ``expect`` as soon as received.
1. configs are not functional
* decorator will be executed when search case, need to set default config before search case.
2. fix DUT encode/decode errors
* python3 serial don't support write string/unicode, need to convert to bytes first.
* python2 string could failed to encode/decode non-acsii chars
3. fix bug that log folder not created
4. fix bug that test suite name is not correctly passed:
* the keyward arg should be `test_suite_name` not `test_name`
5. fix bug that test stopped on failed case
6. fix DUT `read` don't return all data cache
* `_DataCache.get_data` should first copy all data from queue to data cache and then return to user.
7. fix bug that `expect_all` failed even all expected item passed
8. optimize error info for expect
* print pattern for regular expression when match failed
9. fix bug that set default config doesn't work
