add jaeger support, link hot container & req span (#840)

* add jaeger support, link hot container & req span

* adds jaeger support now with FN_JAEGER_URL, there's a simple tutorial in the
operating/metrics.md file now and it's pretty easy to get up and running.
* links a hot request span to a hot container span. when we change this to
sample at a lower ratio we'll need to finagle the hot container span to always
sample or something, otherwise we'll hide that info. at least, since we're
sampling at 100% for now if this is flipped on, can see freeze/unfreeze etc.
if they hit. this is useful for debugging. note that zipkin's exporter does
not follow the link at all, hence jaeger... and they're backed by the Cloud
Empire now (CNCF) so we'll probably use it anyway.

* vendor: add thrift for jaeger

vendor/git.apache.org/thrift.git/test/SmallTest.thrift

@@ -0,0 +1,60 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied. See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+
+namespace rb TestNamespace
+
+struct Goodbyez {
+  1: i32 val = 325;
+}
+
+senum Thinger {
+  "ASDFKJ",
+  "r32)*F#@",
+  "ASDFLJASDF"
+}
+
+struct BoolPasser {
+  1: bool value = 1
+}
+
+struct Hello {
+  1: i32 simple = 53,
+  2: map<i32,i32> complex = {23:532, 6243:632, 2355:532},
+  3: map<i32, map<i32,i32>> complexer,
+  4: string words = "words",
+  5: Goodbyez thinz = {'val' : 36632}
+}
+
+const map<i32,map<i32,i32>> CMAP = { 235: {235:235}, 53:{53:53} }
+const i32 CINT = 325;
+const Hello WHOA = {'simple' : 532}
+
+exception Goodbye {
+  1: i32 simple,
+  2: map<i32,i32> complex,
+  3: map<i32, map<i32,i32>> complexer,
+}
+
+service SmallService {
+  Thinger testThinger(1:Thinger bootz),
+  Hello testMe(1:i32 hello=64, 2: Hello wonk) throws (1: Goodbye g),
+  void testVoid() throws (1: Goodbye g),
+  i32 testI32(1:i32 boo)
+}