Writing an OK message to stdout instead of stderr
[fix] boolean capitalization

Discovered when running `le monitor` on SmartOS on Joyent Cloud.

This fix resolves where the current version causes error:
```py
Exception in thread Thread-1:
Traceback (most recent call last):
  File "/opt/local/lib/python2.7/threading.py", line 810, in __bootstrap_inner
    self.run()
  File "/opt/local/bin/le", line 483, in run
    msg = self.msg_queue.get(true)
NameError: global name 'true' is not defined
```
Fixing true to True
Merge pull request #59 from doublerebel/master

[fix] boolean capitalization
Merge pull request #57 from vilda/use_stdout

Writing an OK message to stdout instead of stderr
Merge pull request #58 from StephenHynes7/master

fix syntax error, fix system stat format
Removing support for Windows
Fixing whitespaces
Merge pull request #61 from vilda/win_remove

Win remove
If stats can not be computed return an empty string
 Remove creation of logentries-system-stat log file during installation