[TEST] Left '.' as it is in REST suites and sections titles (was previously replaced with '_')

With JUnit up to 4.10 there's no way to distinguish between what's shown in IDEs and test ids that need to be unique. A test Description is identified by just a string, that needs to be unique and is shown by IDEs. IDEs have slightly different behaviours when it comes to showing tests and suites titles. Some IDE (e.g. IntelliJ) strips the description on '.', which is why the '.' was replaced in the first place, in order to obtain the same behaviour on all IDEs. On the other hand the information printed out by RestReproduceInfoPrinter was wrong as the file path contained a '_' instead of a '.', which made the string to reproduce a failure useless in some cases. At the end of the day it seems better to just keep the dots and accept slightly different behaviours that are IDE dependent.
[TEST] Added check: test section names must be unique in the same REST test suite

Fixed also three duplicates found
[TEST] Replaced File.separator with '/' as REST test suites can be loaded from classpath, where '/' is needed
[TEST] Added params validation according to REST spec and check whether body is supported or required
[TEST] Removed TODO and custom code now that ping and info are two different apis in the REST spec
[TEST] Wipe templates is now done in a single call using wildcards (compared to cluster state + delete each template)
[SPEC] Added missing cat endpoints. count and recovery
And added missing qs params to health and indices.
Remove the "-f" script argument from the documentation

Closes #4778.
[SPEC] Created snapshot.* and nodes.* namespaces

Moved node_info, node_stats, shutdown and hot_threads into nodes.*
Moved snapshot and repository APIs into snapshot.*
Cleanup tests - using assert method instead of assert keyword
Remove `omit_term_freq_and_positions` for new indices

`omit_term_freq_and_positions` was deprecated in `0.20` and
is not documented anymore. We should reject indices that are
created with this option in the future.

Closes #4722
Add SecurityManger / policy when running tests.

This commit adds a security manager to the test JVMs
that prevents mainly writing files outside of the JVMs
current test directory.
[SPEC] Added missing body object in snapshot apis
Use millis for joda DateTimeFormatter.print()

Fixes #4782.
[SPEC] removing deprecated include/exclude for get_source

_source_include/_source_exclude should be used instead
Removed double masterNodeTimeout set in RestPutRepositoryAction
[TEST] fixed error message in REST tests runner
Check ThreadInfo[] for null element if thread are not alive.

If a thread is not alive getting ThreadMXBean#getThreadInfo(long[], int)
places null elemnents in the returned array which are not repected
in the HotTheards API.

Closes #4775
[SPEC] Removed _source endpoint from get api spec, as the get_source is a different api already

Also removed custom code that was required in the REST tests due to this.
apply line ending fix only on Windows
fix for #4785