v0.0.18 Release

This release includes a new mechanism for doing vulnerability updates and a host of bugfixes.

• #146 Make python package name case insensitive
• #145 fix tar eof
• #144 update diffs
• #143 fastesturl: deflake the test
• #142 Add Alec Merdler to Maintainers
• #140 pkgconfig: add pkg-config scanner
• #139 use alpine dist scanner
• #138 package db idx
• #137 dedupe layers to be scanned
• #136 the empty layer