fix: DayTrader GitLab CI problem (Issue #16)

The problem was because Geronimo server wants to read from stdin.
GitLab runner doesn't provide stdin, so it just reads an EOF and quits.
This is why GBeans is not running.
Thus the solution is to keep stdin open for the duration of the benchmark.
Setting a time out (120 seconds) with `sleep` command seems to work.
NOTE: this value may need to be modified on slower machines.
15 jobs for master in 5 minutes and 15 seconds (queued for 2 seconds)
Status Job ID Name Coverage
  Test
failed #20055
avrora

00:03:30

passed #20056
batik

00:00:31

canceled #20057
eclipse

00:00:18

canceled #20058
fop

canceled #20059
h2

canceled #20060
jython

passed #20061
luindex

00:00:54

canceled #20062
lusearch

canceled #20063
lusearch-fix

canceled #20064
pmd

canceled #20065
sunflow

canceled #20066
tomcat

canceled #20067
tradebeans

canceled #20068
tradesoap

canceled #20069
xalan

 
Name Stage Failure
failed
avrora Test There is an unknown failure, please try again
     [exec] Result: 1
[echo] avrora: FAIL

BUILD FAILED
/home/gitlab-runner/builds/8f85a92c/0/dacapo/anu-dev/dacapobench/benchmarks/build.xml:399: The following error occurred while executing this line:
/home/gitlab-runner/builds/8f85a92c/0/dacapo/anu-dev/dacapobench/benchmarks/build.xml:387: avrora: FAIL

Total time: 3 minutes 29 seconds
ERROR: Job failed: exit status 1