Add valgrind instrumentation support

Modify vector_private test to work with Valgrind instrumentation.

Add const methods to pmem::obj::experimental::array. 

Make persistent atomic fix

Tests for:
- const_at
- cfront
- cback
- cdata
- const version of (r)begin
- const version of (r)end
- const version of range

These operators should be marked const as they do not
modify the iterator.

Add:
- const_at
- cfront
- cback
- cdata

This methods behaves the same as const overloads of at, front,
back and data but can be called on non-const object.

Before this patch all arguments passed to constructor were treated
as lvalue references. This patch fixes that by mainting information
about wheter argument is rvalue of lvalue reference.

Introduce flag parameter to make_persistent(atomic)

fix typo

test: fix sudo issue

Default number of minutes that can elapse before sudo will ask
for a password again is 5. It is too short for our increasing set
of tests.
In this patch we force sudo to ask for a password and provide sudo
with valid password each time.

test: add vector-iter-iter custom test

 Disable some libcxx tests for old g++ compilers.

verify if iter-iter vector ctor will construct vector from
element's type copy ctor

add emplace_constructible_copy_insertable_move_insertable helper class

They cannot be compiled due to lack of full C++11 support.

This was not included in #150 by mistake.

tests: expose env variable for changing pmreorder stacktrace depth

and show pmreorder log on test failure (if the log exists).

vector: change capacity to fit size (in ctors)

Fix gcc trivially copyable

std::is_trivially_copyable is missing in gcc < 5

test: vector copy/move/init_list constructor tests

Vector iterators and access methods

vector: fix transaction error msg

Import llvm tests for string.

test: remove redundant includes and fix comment

this test checks if specyfic access methods can be called
out of transaction scope and if accessed elements are being
snapshotted

test: add vector iterators.pass test

test: add vector contiguous.pass test

test: add vector data_const.pass and data.pass