Add support for minimum OTP versions.

Since you can't really do math with regexps and it's a pain to
repeatedly update the config for each new version or erlang, I wanted
to add support for minium OTP versions.  This is a fix for
https://github.com/basho/riaknostic/issues/38
Add skip_deps=AppListSeparatedByCommas feature
Restore ability to specify deps_dir on the command line

It was previously possible to run `rebar compile deps_dir=/path/to/deps`,
but as of 70d27c5720331076f52e4fd7bcd1dc8045c8c86a, it was nixed.
rebar_deps: fix whitespace errors
Document availability of rsync for fetching deps in rebar.config.sample
Merge pull request #316 from danielwhite/document-rsync-feature

Document availability of rsync for fetching deps in rebar.config.sample
Add Daniel White to THANKS file
Revert 15b7798e4 and restore old git-describe call

Restore previous 'git describe' behaviour as discussed here:
http://lists.basho.com/pipermail/rebar_lists.basho.com/2012-September/001713.html
Fix fprof use (-p/--profile)
deps: add fossil scm support
Add Martin Schut to THANKS file
Fix whitespace errors
noshell/noinput should NOT be the default emulator args for an escript
rebar_edoc: use correct proplist() type (Reported-by: Kostis Sagonas)
Add support for non-Erlang/OTP (raw) dependencies

Introduce a new 'raw' option for dependency specs in rebar.config file.
For example:

{deps,
    {dependency_name, "1.0.*",
	 {git, "<...>", {branch, "master"}},
	 [raw]
    }
]}.

When this option is specified, rebar does not require the dependency to
have a standard Erlang/OTP layout which assumes presence of either
"src/dependency_name.app.src" or "ebin/dependency_name.app" files.

'raw' dependencies can still contain 'rebar.config' and even can have
the proper OTP directory layout, but they won't be compiled.

Only a subset of rebar commands will be executed on the 'raw'
subdirectories:

	get-deps, update-deps, check-deps, list-deps and delete-deps.
Add hostname variable to reltool overlay templates
Fix return value of rebar:overlay/2

When 'rebar overlay' is run rebar_core got a wrong result
{Config, ok} from rebar_reltool instead of {ok, Config}.
Merge pull request #326 from saleyn/hostname_var

Add hostname variable to reltool overlay templates
Merge pull request #325 from saleyn/reltool

Fix return value of rebar_overlay
Adding Serge Aleynikov to THANKS