Default column name to pojo field name, and add `allFields` mode to `Measurement` annotation

[eranl]

if @Column is used without a name, the annotated field's name is used as the column name.

In addition, when a pojo is annotated with @Measurement(name = "...", allFields = true), then all its fields are loaded or saved. Finally, an @Exclude annotation can be used for opting a field out in this mode.

Fixes #971.

[codecov-commenter]

Codecov Report

Attention: 3 lines in your changes are missing coverage. Please review.

Comparison is base (d3a7bbc) 61.22% compared to head (32d31ac) 61.28%.

:exclamation: Current head 32d31ac differs from pull request most recent head aeaba32. Consider uploading reports for the commit aeaba32 to get more accurate results

Files	Patch %	Lines
src/main/java/org/influxdb/dto/Point.java	81.81%	0 Missing and 2 partials :warning:
...n/java/org/influxdb/impl/InfluxDBResultMapper.java	88.88%	0 Missing and 1 partial :warning:

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Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #972 +/- ## ============================================ + Coverage 61.22% 61.28% +0.06% - Complexity 443 450 +7 ============================================ Files 70 70 Lines 2579 2591 +12 Branches 271 277 +6 ============================================ + Hits 1579 1588 +9 Misses 932 932 - Partials 68 71 +3 ```

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[majst01]

Nice PR, thanks for you contribution, can you please also add a bit of documentation of you new features, best place would be here.

If this is done, i am happy to merge

[eranl]

can you please also add a bit of documentation of you new features, best place would be here.

Updated. Please review.