Fix a couple of tests

[ixje]

What current issue(s) does this address, or what feature is it adding?
There are a couple of tests that didn't work as intended under certain conditions, had uncaught exceptions or otherwise. This cleans up a couple of them

1. This test was passing but internally had an exception that shows up in logs
   

   neo-python/neo/Prompt/Commands/tests/test_send_command.py

   Line 91 in 773e57e

   def test_6_weird_amount(self):

2. This test would cause a 404 error on downloading, while actually expected it kept triggering me to look into why.
   https://github.com/CityOfZion/neo-python/blob/master/neo/Prompt/Commands/tests/test_bootstrap.py#L24

3. This test would fail if your configured theme is light instead of the default dark
   

   neo-python/neo/test_preferences.py

   Line 22 in 773e57e

   def test_prefs_json_empty(self):

4. one test used the deprecated assertEquals instead of assertEqual which kept throwing a warning

5. the BlockchainFixtureTestCase and WalletFixtureTestCase relied on running the tests from the root folder. My IDE (PyCharm) executes from whatever file I press run test and for tests using either of the before mentioned cases it would fail to find wallets due to the relative path construction e.g.
   

   neo-python/neo/Utils/WalletFixtureTestCase.py

   Lines 14 to 15 in 773e57e

   	def wallet_1_path(cls):
   	return './fixtures/neo-test1-w.wallet'

How did you solve this problem?

1. catch exception
2. don't assume default theme, but actually read what theme is configured
3. added a clear notification indicating the test shows an error
4. use assertEqual
5. detect root folder and create absolute paths.

How did you make sure your solution works?
make test

Are there any special changes in the code that we should be aware of?
no
Please check the following, if applicable:

• Did you add any tests?
• Did you run make lint?
• Did you run make test?
• Are you making a PR to a feature branch or development rather than master?
• [] Did you add an entry to CHANGELOG.rst? (if not, please do)

[coveralls]

Coverage decreased (-0.1%) to 81.278% when pulling 390fd94 on ixje:fix_tests into 69bead6 on CityOfZion:development.

[jseagrave21]

Good fixes. I also caught the Prompt.Commands.Send fix. It is included in #610

[jseagrave21]

@ixje Hey, should there have been an update to the changelog?

[ixje]

I initially chose not to do it because it was 2 minor fixes, then extended it with 2 more. I'm ok without a changelog on these. Most will not notice it as they've been there for such a long time.