Add Plugins#__str__

Because when doing jenkins.get_plugins() in an interactive python shell,
the behavior was to use the JenkinsBase#__str__ which throws a
NotImplementedError
ensure virtualenv installed and WORKSPACE defined
Fetch full build list when incomplete

By default, Jenkins returns the last 100 builds. If there are more
builds, an extra api call is made to have all builds in the job object
Merge pull request #175 from Smartesting/fetch_all_builds

Fetch full build list of job when incomplete
add support for FILE parameters.

if a job requires file paremeters, then we cannot use the /build form to
request the build, we need to switch to the /buildWithParameters trigger
and provide a multipart encoded upload.

thankfully requests library has all the plumbing.
Fix whitespace issues
Add trailing newline in file
Fix whitespace around operators
Split lines joined by semicolon
Remove use of has_key
Fix indentation of block
Fix really long lines
Reformat __all__
Change import for pylint error
Add pep8 and pylint to .travis.yml
Add pylint config
Fix over-indentation
Remove unneeded imports
Merge multiple docstrings
Use list comprehension; split long lines