[AIRFLOW-2335] fix issue with jdk8 download for ci
[AIRFLOW-2335] fix issue with jdk8 download for ci

Make sure you have checked _all_ steps below.

- [x] My PR addresses the following [Airflow JIRA]
(https://issues.apache.org/jira/browse/AIRFLOW/)
issues and references them in the PR title. For
example, "\[AIRFLOW-XXX\] My Airflow PR"
    -
https://issues.apache.org/jira/browse/AIRFLOW-2335
    - In case you are fixing a typo in the
documentation you can prepend your commit with
\[AIRFLOW-XXX\], code changes always need a JIRA
issue.

- [x] Here are some details about my PR, including
screenshots of any UI changes:

There is an issue with travis pulling jdk8 that is
preventing CI jobs from running. This blocks
further development of the project.

Reference: https://github.com/travis-ci/travis-
ci/issues/9512#issuecomment-382235301

- [x] My PR adds the following unit tests __OR__
does not need testing for this extremely good
reason:

This PR can't be unit tested since it is just
configuration. However, the fact that unit tests
run successfully should show that it works.

- [ ] My commits all reference JIRA issues in
their subject lines, and I have squashed multiple
commits if they address the same issue. In
addition, my commits follow the guidelines from
"[How to write a good git commit
message](http://chris.beams.io/posts/git-
commit/)":
    1. Subject is separated from body by a blank line
    2. Subject is limited to 50 characters
    3. Subject does not end with a period
    4. Subject uses the imperative mood ("add", not
"adding")
    5. Body wraps at 72 characters
    6. Body explains "what" and "why", not "how"

- [ ] In case of new functionality, my PR adds
documentation that describes how to use it.
    - When adding new operators/hooks/sensors, the
autoclass documentation generation needs to be
added.

- [ ] Passes `git diff upstream/master -u --
"*.py" | flake8 --diff`

Closes #3236 from dimberman/AIRFLOW-
2335_travis_issue

cfei18/incubator-airflow,edgarRd/incubator-airflow,cfei18/incubator-airflow,criccomini/airflow,wolfier/incubator-airflow,wndhydrnt/airflow,akosel/incubator-airflow,danielvdende/incubator-airflow,jgao54/airflow,spektom/incubator-airflow,fenglu-g/incubator-airflow,bolkedebruin/airflow,edgarRd/incubator-airflow,mrkm4ntr/incubator-airflow,wileeam/airflow,mrkm4ntr/incubator-airflow,wileeam/airflow,Fokko/incubator-airflow,apache/airflow,Tagar/incubator-airflow,Acehaidrey/incubator-airflow,cfei18/incubator-airflow,subodhchhabra/airflow,subodhchhabra/airflow,dhuang/incubator-airflow,wooga/airflow,mistercrunch/airflow,apache/incubator-airflow,akosel/incubator-airflow,jgao54/airflow,bolkedebruin/airflow,jgao54/airflow,r39132/airflow,malmiron/incubator-airflow,dhuang/incubator-airflow,apache/airflow,owlabs/incubator-airflow,malmiron/incubator-airflow,DinoCow/airflow,yk5/incubator-airflow,sergiohgz/incubator-airflow,subodhchhabra/airflow,adamhaney/airflow,danielvdende/incubator-airflow,lyft/incubator-airflow,akosel/incubator-airflow,owlabs/incubator-airflow,apache/airflow,artwr/airflow,wolfier/incubator-airflow,criccomini/airflow,CloverHealth/airflow,wooga/airflow,mistercrunch/airflow,yk5/incubator-airflow,wileeam/airflow,sekikn/incubator-airflow,CloverHealth/airflow,danielvdende/incubator-airflow,fenglu-g/incubator-airflow,edgarRd/incubator-airflow,fenglu-g/incubator-airflow,apache/airflow,sekikn/incubator-airflow,sergiohgz/incubator-airflow,cfei18/incubator-airflow,CloverHealth/airflow,apache/incubator-airflow,lxneng/incubator-airflow,jgao54/airflow,Fokko/incubator-airflow,Acehaidrey/incubator-airflow,cfei18/incubator-airflow,wndhydrnt/airflow,DinoCow/airflow,Fokko/incubator-airflow,sekikn/incubator-airflow,criccomini/airflow,airbnb/airflow,andyxhadji/incubator-airflow,dhuang/incubator-airflow,sid88in/incubator-airflow,mistercrunch/airflow,Tagar/incubator-airflow,nathanielvarona/airflow,lxneng/incubator-airflow,artwr/airflow,mtagle/airflow,edgarRd/incubator-airflow,RealImpactAnalytics/airflow,mtagle/airflow,wooga/airflow,nathanielvarona/airflow,nathanielvarona/airflow,apache/incubator-airflow,gtoonstra/airflow,Acehaidrey/incubator-airflow,airbnb/airflow,Fokko/incubator-airflow,sid88in/incubator-airflow,lyft/incubator-airflow,r39132/airflow,wolfier/incubator-airflow,RealImpactAnalytics/airflow,yk5/incubator-airflow,wileeam/airflow,nathanielvarona/airflow,nathanielvarona/airflow,nathanielvarona/airflow,lxneng/incubator-airflow,artwr/airflow,sergiohgz/incubator-airflow,owlabs/incubator-airflow,danielvdende/incubator-airflow,r39132/airflow,andyxhadji/incubator-airflow,wndhydrnt/airflow,andyxhadji/incubator-airflow,mrkm4ntr/incubator-airflow,mtagle/airflow,bolkedebruin/airflow,spektom/incubator-airflow,andyxhadji/incubator-airflow,subodhchhabra/airflow,yk5/incubator-airflow,bolkedebruin/airflow,mistercrunch/airflow,malmiron/incubator-airflow,wolfier/incubator-airflow,malmiron/incubator-airflow,bolkedebruin/airflow,akosel/incubator-airflow,RealImpactAnalytics/airflow,lyft/incubator-airflow,DinoCow/airflow,Acehaidrey/incubator-airflow,airbnb/airflow,spektom/incubator-airflow,Tagar/incubator-airflow,owlabs/incubator-airflow,wooga/airflow,apache/airflow,fenglu-g/incubator-airflow,Acehaidrey/incubator-airflow,adamhaney/airflow,cfei18/incubator-airflow,adamhaney/airflow,spektom/incubator-airflow,wndhydrnt/airflow,criccomini/airflow,CloverHealth/airflow,dhuang/incubator-airflow,danielvdende/incubator-airflow,RealImpactAnalytics/airflow,apache/airflow,Tagar/incubator-airflow,sergiohgz/incubator-airflow,DinoCow/airflow,r39132/airflow,sekikn/incubator-airflow,airbnb/airflow,gtoonstra/airflow,gtoonstra/airflow,mrkm4ntr/incubator-airflow,mtagle/airflow,lxneng/incubator-airflow,adamhaney/airflow,lyft/incubator-airflow,apache/incubator-airflow,Acehaidrey/incubator-airflow,artwr/airflow,danielvdende/incubator-airflow,gtoonstra/airflow,sid88in/incubator-airflow,sid88in/incubator-airflow