Remove synonymous names for 'fluxsite'

[SeanBryan51]

Currently, there is inconsistent naming conventions being used to describe fluxsite tests which can be confusing for developers and users. These include names such as 'site', 'single site', 'fluxsite', 'fluxnet', etc. This change replaces all occurrences of these names in the code base and documentation with 'fluxsite'.

We choose 'fluxsite' as this describes the nature of the tests (as opposed to 'fluxnet' which describes a product/network).

Fixes #62

[codecov]

Codecov Report

Merging #111 (b829293) into master (8acd685) will not change coverage.
The diff coverage is 79.31%.

@@           Coverage Diff           @@
##           master     #111   +/-   ##
=======================================
  Coverage   88.26%   88.26%           
=======================================
  Files          26       26           
  Lines        1364     1364           
=======================================
  Hits         1204     1204           
  Misses        160      160           

Impacted Files	Coverage Δ
benchcab/cli.py	100.00% <ø> (ø)
benchcab/comparison.py	61.36% <ø> (ø)
benchcab/utils/pbs.py	100.00% <ø> (ø)
tests/test_pbs.py	100.00% <ø> (ø)
benchcab/benchcab.py	35.06% <27.58%> (ø)
benchcab/internal.py	90.47% <80.00%> (ø)
benchcab/task.py	83.00% <87.50%> (ø)
benchcab/benchtree.py	100.00% <100.00%> (ø)
tests/test_benchcab.py	100.00% <100.00%> (ø)
tests/test_benchtree.py	100.00% <100.00%> (ø)
... and 3 more

[ccarouge]

All good.