Switch to rebar3 while keeping backward compatibility to rebar2

.gitignore

@@ -12,3 +12,4 @@ dump.rdb
 .rebar
 _rel
 relx
+_build

rebar.config

@@ -5,6 +5,6 @@
 }.
 {cover_enabled, true}.
 {deps, [
-     {lager, ".*", {git, "https://github.com/basho/lager.git", {tag, "3.0.1"}}}
-    ,{jsx,   "2.*", {git, "https://github.com/talentdeficit/jsx.git", {tag, "v2.7.1"}}}
+     {lager, "3.0.1"}
+    ,{jsx,   "2.7.1"}
 ]}.

rebar.config.script

@@ -0,0 +1,11 @@
+case erlang:function_exported(rebar3, main, 1) of
+    true -> % rebar3
+        CONFIG;
+    false -> % rebar 2.x or older
+        %% Rebuild deps, possibly including those that have been moved to
+        %% profiles
+        [{deps, [
+            {lager, ".*", {git, "https://github.com/basho/lager.git", {tag, "3.0.1"}}}
+           ,{jsx,   ".*", {git, "https://github.com/talentdeficit/jsx.git", {tag, "v2.7.1"}}}
+        ]} | [Config || {Key, _Value}=Config <- CONFIG, Key =/= deps]]
+end.

rebar.lock

@@ -0,0 +1,10 @@
+{"1.1.0",
+[{<<"goldrush">>,{pkg,<<"goldrush">>,<<"0.1.7">>},1},
+ {<<"jsx">>,{pkg,<<"jsx">>,<<"2.7.1">>},0},
+ {<<"lager">>,{pkg,<<"lager">>,<<"3.0.1">>},0}]}.
+[
+{pkg_hash,[
+ {<<"goldrush">>, <<"349A351D17C71C2FDAA18A6C2697562ABE136FEC945F147B381F0CF313160228">>},
+ {<<"jsx">>, <<"30CA834AC0AC6D745E4103D62CCC123C81399E4C937B7751A0185EF16425EDA8">>},
+ {<<"lager">>, <<"480F0DFF5A53EBD5937EF6B469B18BC776F911BD0A8B29328900BA3E8BBF63C6">>}]}
+].