Fix bug where header.name is not set

[kinverarity1]

If the LAS file has no entry for ~Well WELL. then header.name is never set and w.plot() fails with an error.

Example LAS file: https://gist.githubusercontent.com/kinverarity1/2d2ae81f41b0e8c9e0022e0fc990f832/raw/0a387ac27b0b45725e9ba6cfe156398f70e2a4fe/example.las

>>> import welly
>>> w = welly.Well.from_las(r"c:\users\kinverarity\Documents\scratch2016\welly_bug_depth\example.las")
>>> w._repr_html_()
'<table><tr><th style="text-align:center;" colspan="2"><br><small>unknown</small></th></tr><tr><td><strong>crs</strong></td><td>CRS({})</td></tr><tr><td><strong>td</strong></td><td>None</td></tr><tr><td><strong>data</strong></td><td>Cali, Dens, Gamm, Late, Neut, PntR, Spon</td></tr></table>'
>>> w.plot()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "C:\Program Files (x86)\Misc\kentcode\welly\welly\well.py", line 427, in plot
    fig.suptitle(self.header.name, size=16, zorder=100,
AttributeError: 'Header' object has no attribute 'name'
>>>

Fixed it by setting header.name = 'unknown' in the Header.__init__ method before the passed arguments are set.

[kwinkunks]

I have no excuses for this taking me so long to deal with. This was implemented in current dev (setting as empty string, instead of 'unknown'. Did the same for the UWI.

Thank you Kent!

[kinverarity1]

All good, thanks!