Merge branch 'jk/credentials'

* jk/credentials: t: add test harness for external credential helpers credentials: add "store" helper strbuf: add strbuf_add*_urlencode Makefile: unix sockets may not available on some platforms credentials: add "cache" helper docs: end-user documentation for the credential subsystem credential: make relevance of http path configurable credential: add credential.*.username credential: apply helper config http: use credential API to get passwords credential: add function for parsing url components introduce credentials API t5550: fix typo test-lib: add test_config_global variant Conflicts: strbuf.c