Adding suffix methods and properties

[henryiii]

The suffix, suffixes properties andwith_name, with_suffix methods were added
(names chosen to be similar to other packages, like the builtin pathlib). One
difference vs. pathlib is an optional parameter for the with_suffix method that
allows simple manipulation of extended suffixes, like .tar.gz.

These additions are useful for working with multiple files of the same name,
such as when compiling programs or documents, and for packing/changing
compressed files.

Documentation, local and remote (and base class) support, unittests, and an
example were added.

As a quick example, here is .tar.gz -> .zip conversion, adopted from the bash script at http://stackoverflow.com/questions/6301885/convert-tar-gz-to-zip :

from plumbum import local
from plumbum.cmd import tar, zip, mkdir, rm
files = local.cwd // "*.tar.gz"
for file in files:
    tmpfolder = file.with_suffix(".tmp", 0) # .tar.gz.tmp temporary folder
    mkdir(tmpfolder)
    tar("-C", tmpfolder, "-xvzf", file)
    with local.cwd(tmpfolder):
        zip("-r", file.with_suffix(".zip", 2), ".")
    rm("-rf", tmpfolder)

And this would compile a tex file and remove the extra files generated:

from plumbum.cmd import pdflatex
from plumbum.path.utils import delete
from plumbum import local, FG
item = local.cwd / "document.tex"
pdflatex[item] & FG
delete(item.with_suffix(".log"), item.with_suffix(".aux"))