unpack_url: session only needed for unpack_http_url
vcs: add documentation to VersionControl class
cleanup: use "with open()" to open files
freeze: simplify code and use with open()
Merge pull request #2034 from xavfernandez/xfernandez/small_improvments

Small improvements
remove tag_svn_revision to fix test, same as PR #2045
Merge pull request #2116 from bukzor/buck-remove-tag-svn-revision

remove tag_svn_revision to fix test, same as PR #2045
Use a secure randomized build directory when possible
Merge pull request #2122 from dstufft/randomized-build-directory

Use a secure randomized build directory when possible
Add the CVE for the randomized build directory
Properly handle equality of Link objects with other objects
Alias the "real" names as pip._vendor.* when the vendored are missing
Use a real install instead of develop
Conditionally install the pip._vendor items
Test unvendoring on Travis
Add a warning to the setup.py if used with no bundled
Address Feedback from @ncoghlan
Update the bundling documentations
Document the loss of ftp:// and remove some left over code from it
Merge pull request #2133 from dstufft/document-ftp

Document the loss of ftp:// and remove some left over code from it