trying to stop loop

isolating postgres calls

Separating jobs

Separating builds again

Just added back version 10, just in case it gets called

Removed postgres installs from unneeded test cases. Added the ability to test Postgres 10 and 11

Added test for postgres 12 that's allowed to fail

Second round to see if it fails eventually

Round 3

Allowing all postgres to fail since it seems to occur randomly

Now the mongo and postgres scripts are independent of each other to prevent the `ERROR:  could not access file "$libdir/postgis-2.4": No such file or directory` of showing up in the rest of the builds.

In addition, a test for postgres-12 has been added for future compatibility. Both the postgres-11 and postgres-12 have been added to `allow_failures` because the aforementioned error still creeps up. Important note is that the error has nothing to do with compatibility with postgres, but rather seems to be an error of how postgres (or really postgis) is being referenced in the respective travis distribution. Lastly, this error, if truly random should appear less than before as the postgres scripts aren't being run for every build as it previously was running.

Seeing if this gets rid of the random error

Removing the native postgres builds at the right time seems to have fixed the random error from before.

The postgres tests are now not allowed to fail.

The actual problem is fixed, but it seems there are some instability with some of the test cases for postgres that need to be addressed at another time.

The issues that pop up are: 
- Postgres-11
```Failures:
1) Cloud Code cloud jobs should set the message / success on the job
  Message:
    Expected undefined to equal 'hello'.
  Stack:
    Error: Expected undefined to equal 'hello'.
        at <Jasmine>
        at req.message.then.then.jobStatus (/home/travis/build/parse-community/parse-server/spec/CloudCode.spec.js:1571:46)
        at process._tickCallback (internal/process/next_tick.js:68:7)
```

- Postgres-12
``` 
Failures:
1) Cloud Code cloud jobs should set the message / success on the job
  Message:
    Expected undefined to equal 'hello'.
  Stack:
    Error: Expected undefined to equal 'hello'.
        at <Jasmine>
        at req.message.then.then.jobStatus (/home/travis/build/parse-community/parse-server/spec/CloudCode.spec.js:1571:46)
        at process._tickCallback (internal/process/next_tick.js:68:7)
  Message:
    Expected 'running' to equal 'succeeded'.
  Stack:
    Error: Expected 'running' to equal 'succeeded'.
        at <Jasmine>
        at promise.then.then.jobStatus (/home/travis/build/parse-community/parse-server/spec/CloudCode.spec.js:1580:45)
        at process._tickCallback (internal/process/next_tick.js:68:7)
```

This should shrink the footprint of the file and and reduce the redundancy of calls for postgres.

Added support for testing of Postgres 9 and 10 in the scripts, not adding the tests though

removed old lines

…ot have to remove anything from the image

…using PARSE_SERVER_TEST_DATABASE_URI

…nfig instead.

…s to skip remove