jdbc: fix tests on tarantool 2.1

[ztarvos]

Updated jdbc tests following static SQL types
introduction into tarantool 2.1.

Closes #90

[coveralls]

Pull Request Test Coverage Report for Build 100

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 23 unchanged lines in 5 files lost coverage.
• Overall coverage decreased (-0.3%) to 62.47%

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Files with Coverage Reduction	New Missed Lines	%
src/main/java/org/tarantool/TarantoolClientImpl.java	1	82.88%
src/main/java/org/tarantool/jdbc/SQLMsgPackLite.java	2	83.33%
src/main/java/org/tarantool/jdbc/SQLResultSet.java	5	17.98%
src/main/java/org/tarantool/MsgPackLite.java	5	78.18%
src/main/java/org/tarantool/jdbc/SQLPreparedStatement.java	10	33.66%

Totals
Change from base Build 99:	-0.3%
Covered Lines:	1295
Relevant Lines:	2073

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💛 - Coveralls

[Totktonada]

I found names within TestHelper too common (it was a bit tricky for me to get the idea from them), but I don't think it worth to do one more review iteration because of that (I think we can be quite tolerable against testing code).

I think that we possibly miss to test cases like 2^64 for INT Tarantool/SQL type (see mapping on the wiki). But this is out of scope of this issue and we'll do it in the scope of #92.

Don't sure we should test storing dates within ints, but there are no other way now, so it does not much matter.

There were two other changes in Tarantool that breaks some tests, I'll push fixes to the master branch on top of this one.

Thank you, Sergei!