In response to: IOTSFW-325 ...

1. Removed globaly initialized data inside class test() function
2. Removed global variables initialization dependency. Any cause some Python
   implementations and configurations to fail in runtime
3. Added info about Echo port #7 rationale.
4. Testsed with K64F and network tests:

Test summary:
+--------+--------+---------+----------------------------+--------------------+
| Result | Target | Test ID | Test Description           | Elapsed Time (sec) |
+--------+--------+---------+----------------------------+--------------------+
| OK     | K64F   | NET_1   | TCP client hello world     |        3.26        |
| OK     | K64F   | NET_13  | TCP client echo loop       |        2.05        |
| OK     | K64F   | NET_2   | NIST Internet Time Service |        3.43        |
| OK     | K64F   | NET_3   | TCP echo server            |        1.54        |
| OK     | K64F   | NET_4   | TCP echo client            |        1.54        |
| OK     | K64F   | NET_5   | UDP echo server            |        1.46        |
| OK     | K64F   | NET_6   | UDP echo client            |        1.6         |
| OK     | K64F   | NET_7   | HTTP client hello world    |        3.4         |
| OK     | K64F   | NET_8   | NTP client                 |        2.39        |
+--------+--------+---------+----------------------------+--------------------+
Result: 9 OK

Completed in 122.18 sec

Added NET_4, NET_6 and NET_13 tests to autodetection pool

Host test plugins: Ethernet tests (NET_*) refactored to new host test copy paradigm

Host test refactoring ...

Host test refactoring: replaced magic values of test results returned by host test

Prints with stdout.flush() replaced with notify function

Host test refactoring: created separate enum like class for test result strings

Modified host tests to use serial.realine() function to avoid extra timeouts during tests (test will work faster and will be more reliable)

Fixed NET_(4,6,13) client tests so after reset we wait for device to send print it's ready ...

Fixed small print issue with -V option

Host test: wrapped mbed.serial.timeout into separate function to avoid traceback and send proper IO_SERIAL error from host test(s)

pyFlakes issues fixed. Simple refactoring

Added implementation for TCP and UDP client