bs4: Add beautifulsoup 4.3.2 to assist the fetcher

Added Beautifulsoup module because fetch/wget latest_versionstring
method depends on it.

This provides support to fetch/wget.py module for search new package
versions in upstream sites.

Signed-off-by: Aníbal Limón <anibal.limon@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
fetch/git: Add latest_versionstring method

Being able to generate a version string representing the most recent git commit
given git is useful, not least for the package reporting system.

This adds in a latest_versionstring method to the git fetcher
which allows users to query the latest version using ls-remote
and filtering the responses.

The patch also adds unittests for this function so that if
improvements are made, the original test urls can be used
to evaulate the those changes.

This is based on code from Irina Patru <irina.patru@intel.com>.

Signed-off-by: Saul Wold <sgw@linux.intel.com>
Signed-off-by: Aníbal Limón <anibal.limon@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
fetch/wget: Add latest_versionstring method

Being able to query whether updated versions of a url are available
is useful, not least for the package reporting system. Since such code
is closely linked to the url type and the url itself, the fetcher
makes a locical place to contain this code.

For wget based urls this means taking upstream directory listings
and searching those for later versions, returning those that are
found.

The patch also adds unittests for this function so that if
improvements are made, the original test urls can be used
to evaulate the those changes.

This is based on code from Irina Patru <irina.patru@intel.com>.

Signed-off-by: Aníbal Limón <anibal.limon@linux.intel.com>
Signed-off-by: Saul Wold <sgw@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>