Add cscope: target to toplevel makefile

Runs the cscope tool to build tags for vi.
Document the UKS and GC functions
Merge pull request #141 from gnb/docs2

Doocumenting droplet - 2nd tranche
minor: remove useless file
doc: update .gitignore
 droplet: API simplification
remove test buffered file
remove empty files
Merge pull request #144 from scality/scality_svn

Scality svn
adding swift to backends
Merge branch 'master' of https://github.com/scality/Droplet

add swift to backends

Conflicts:
	libdroplet/Makefile.am
backend.c
compile
Git-ignore some build products in examples/
Fix trace in dpl_req_gen_http_request()

Which was using var->val->string like it was before it became an sbuf.
Print an error message when hostname lookup fails

Because that's either a DNS problem or a misconfiguration, and thus
something we want to know about, unlike a failure to connect to the host
itself.
Simplify dpl_profile_load()

We don't need 2 'ret' variables, one is enough.  Nor do we need to smash
called functions' error results down to DPL_FAILURE just yet, our caller
will do that just fine.
Add dpl_ctx_new_from_dict()

which creates a context using profile information from a dict
rather than reading from a file.
Fix inconsistency in dpl_sysmd_print()

print everything to the passed FILE* rather than emitting some things
directly to stdout.
Fix inconsistency in buf_point_error()

Errors in the pricing model file were reported partly to stderr and
partly to stdout.  Report them entirely to stderr.