Term Vectors: More consistent naming for term vector[s]

We speak of the term vectors of a document, where each field has an associated
stored term vector. Since by default we are requesting all the term vectors of
a document, the HTTP request endpoint should rather be called `_termvectors`
instead of `_termvector`. The usage of `_termvector` is now deprecated, as
well as the transport client call to termVector and prepareTermVector.

Closes #8484
DateMath: Fix semantics of rounding with inclusive/exclusive ranges.

Date math rounding currently works by rounding the date up or down based
on the scope of the rounding.  For example, if you have the date
`2009-12-24||/d` it will round down to the inclusive lower end
`2009-12-24T00:00:00.000` and round up to the non-inclusive date
`2009-12-25T00:00:00.000`.

The range endpoint semantics work as follows:
* `gt` - round D down, and use > that value
* `gte` - round D down, and use >= that value
* `lt` - round D down, and use <
* `lte` - round D up, and use <=

There are 2 problems with these semantics:
* `lte` ends up including the upper value, which should be non-inclusive
* `gt` only excludes the beginning of the date, not the entire rounding scope

This change makes the range endpoint semantics symmetrical.  First, it
changes the parser to round up and down using the first (same as before)
and last (1 ms less than before) values of the rounding scope.  This
makes both rounded endpoints inclusive. The range endpoint semantics
are then as follows:
* `gt` - round D up, and use > that value
* `gte` - round D down, and use >= that value
* `lt` - round D down, and use < that value
* `lte` - round D up, and use <= that value

closes #8424
closes #8556
Fix compile error from bad merge in #8556
Fix test failures caused by #8556
Fix wrong error messages in MultiMatchQueryParser.

Also fix a typo in the comment

Close #8597
Fix a typo in a javadoc comment in MapperService.

Close #8575
[TEST] all tests should extend ElasticsearchTestCase
Added utility method to CountRequestBuilder

Allows to add a query to CountRequestBuilder as a XContentBuilder.

Closes #8594
[STORE] Use Lucene checksums if segment version is >= 4.9.0

We started to use the lucene CRC32 checksums instead of the legacy Adler32
in `v1.3.0` which was the first version using lucene `4.9.0`. We can safely
assume that if the segment was written with this version that checksums
from lucene can be used even if the legacy checksum claims that it has a Adler32
for a given file / segment.

Closes #8587

Conflicts:
	src/main/java/org/elasticsearch/index/store/Store.java
	src/test/java/org/elasticsearch/index/store/StoreTest.java