Release 1.8 (clustershell#360)

http://clustershell.readthedocs.io/en/v1.8/release.html

Closes clustershell#360

Change-Id: I0db2b382d9c2c4be2845c023a639f80323e34316

Release 1.7.3

Change-Id: I6d2d81aa4215963d867bd6c85be8f8f6d8942fe2

Release 1.7.2

Change-Id: I5c58391aadb8cc663a72c6659a2370a8c9fec25c

Release 1.7.1

Change-Id: I67e4b9ee72ae12ff2de45ad500c57e1127dd475b

Release 1.7

Change-Id: I8ba7b1ff5d793cc4f8af4227000302a5530e7b61

Update setuptools/pypi version to 1.6 (sorry)

Release 1.5.1.

Add 1.4.3 tag.

Add 1.4.2 tag.

Add 1.4.1 tag.