test: add upload of integration logs from TravisCI builds

This commit adds adds: 

- Functionality to `gotest.sh` to log the output of `lnd` instances used for
  integration testing to file.

- Uploading of those log files to [termbin.com ](http://www.termbin.com) from
  TravisCI integration builds.

As an example of a build with this enabled, you can look at [this
build](https://travis-ci.org/samvrlewis/lnd/builds/286942025), which is a build
from my `ci_logging_test` branch. That branch has the same diff as my
`ci_logging` branch but with a small inclusion to allow TravisCI builds to work
(as I described in [my
comment](https://github.com/lightningnetwork/lnd/issues/302#issuecomment-335133834)
the other day). If you scroll to the end of the job logs where `RACE=false`
you'll see a `after_script` section with an output like this:

```
output0.log uploaded to http://termbin.com/aloqr
output1.log uploaded to http://termbin.com/3ggh
output2.log uploaded to http://termbin.com/abb9
output3.log uploaded to http://termbin.com/rk9j
output4.log uploaded to http://termbin.com/956p
output5.log uploaded to http://termbin.com/iwwt
```

Fixes #302.

.travis.yml

@@ -17,8 +17,13 @@ install:
   - popd
   - popd
 env:
-  - RACE=false
-  - RACE=true
+  global:
+    - LOGS=true
+  matrix:
+    - RACE=false
+    - RACE=true
 script:
   - export PATH=$PATH:$HOME/gopath/bin
   - ./gotest.sh
+after_script:
+  - find *.log | xargs -I{} sh -c "cat {} | nc termbin.com 9999 | xargs -r0 printf '{} uploaded to %s'"

gotest.sh

@@ -113,19 +113,22 @@ NEED_LINT="false"
 NEED_COVERAGE="false"
 NEED_RACE="false"
 NEED_INSTALL="false"
+NEED_LOGS="false"
 
-while getopts "lrci" flag; do
+while getopts "lrcio" flag; do
         case "${flag}" in
             l) NEED_LINT="true" ;;
             r) NEED_RACE="true" ;;
             c) NEED_COVERAGE="true" ;;
             i) NEED_INSTALL="true" ;;
+            o) NEED_LOGS="true" ;;
             *)
-                printf '\nUsage: %s [-l] [-r] [-c] [-i], where:\n' $0
+                printf '\nUsage: %s [-l] [-r] [-c] [-i] [-o], where:\n' $0
                 printf ' -l: include code lint check\n'
                 printf ' -r: run tests with race condition check\n'
                 printf ' -c: run tests with test coverage\n'
                 printf ' -i: reinstall project dependencies\n'
+                printf ' -o: generate logs for spawned lnd instances\n'
                 exit 1 ;;
         esac
     done
@@ -164,7 +167,13 @@ fi
 # we may calmly send coverage profile (if script is run on travis)
 if [ "$NEED_COVERAGE" == "true" ] || [ "$RACE" == "false" ]; then
     print "* Running integration tests"
-    go test -v -tags rpctest
+
+    LOGOUTPUT_FLAG=""
+    if [ "$NEED_LOGS" == "true" ] || [ "$LOGS" == "true" ]; then
+        LOGOUTPUT_FLAG="-logoutput=true"
+    fi
+
+    go test -v -tags rpctest "$LOGOUTPUT_FLAG"
 
     test_with_coverage_profile
 fi