Only warn for mis-versioned packages.

Allows Package==dev in requirements.
Moved configuration and logging to .config for XDG compliance
Fixed commit #1 to actually work
Switched to use XDG_CONFIG_DIR environment variable if possible (default to ~/.config if not)
Added migration path from ~/.pip to ~/.config/pip
update travis.yml
modify the hashing functions so that they accept any of the guarenteed hashers
remove md5 from backwards compat
fix a typo
Update .travis.yml to remove my changes to it
Issue a warning for an unsuported hash type and catch TypeError as well
Test getting a hash from a file
Test for Valid and Invalid hashes to properly work
Test when the Hash and the Download Link (somehow) are different types
Minor fixes
Fixes to src and build dir locations

Moved src_dir back to cwd for now. build_dir is still created in the
system's temporary dir (tempfile.gettempdir()), but always as
"pip-build".
Revert "Fixes to src and build dir locations"

This reverts commit 20f8ce289d06747c49c348919f201da0a3da6236.
Fixes to build and src dir locations
Merge pull request #565 from harobed/develop

Append documentation about comment line in requirements file format #564
Re-added try/except around src_prefix