Fix error with non unicode chars in serial port description

examples/wiring-blink/.gitignore

@@ -1,2 +1,3 @@
 .pioenvs
 .clang_complete
+.gcc-flags.json

platformio/__init__.py

@@ -14,7 +14,7 @@
 
 import sys
 
-VERSION = (2, 8, "0.dev3")
+VERSION = (2, 8, "0.dev4")
 __version__ = ".".join([str(s) for s in VERSION])
 
 __title__ = "platformio"

platformio/util.py

@@ -272,7 +272,8 @@ def get_serialports():
         from serial.tools.list_ports import comports
     except ImportError:
         raise exception.GetSerialPortsError(os.name)
-    result = [{"port": p, "description": d, "hwid": h}
+    result = [{"port": p, "description": unicode(d, errors='ignore'),
+               "hwid": h}
               for p, d, h in comports() if p]
     # fix for PySerial
     if not result and system() == "Darwin":