all: Refactoring work with time using boost::chrono

Now the library has two clocks: time::steady_clock and
time::system_clock, following (boost|std)::chrono.  In addition to
standard now() method, the library contains several helpers to convert
to/from UnixTimestamp (microsecond resolution) and IsoString (optional
microsecond resolution).  The IsoString conversions use
boost::posix_time routines, since boost::chrono supports extended IO
support only starting boost version 1.52 (Boost Chrono V2).

This commit breaks compatibility with previous API.  All time-related
Data/Interest calls must explicitly use time units to specify
FreshnessPeriod/InterestLifetime.

Brief usage/conversion guide:

- creation of time units does not support double/float types.  If
  necessary to create time unit from double, ``ndn::duration<double>`` (for
  seconds) needs to be used instead.  In some cases, this would also
  require ``ndn::duration_cast``, if the target is not ``ndn::nanoseconds``.
- ndn::getNow, ndn::ndn_getNowMilliseconds, ndn::time::now are all
  removed in favor of the now() method in a specific clock:

    * time::system_clock::now();
    * time::steady_clock::now();

- When necessary to convert system_clock::TimePoint to unix timestamp,
  ``time::toUnixTimestamp`` can be used.  This method return number of
  milliseconds since UNIX epoch as ``ndn::time::milliseconds`` type.
  Use count() method to obtain number as an integral value.

Change-Id: Icd688bc6766e008d60c3d2888173627874526e47
Refs: #1152
diff --git a/tests-integrated/wscript b/tests-integrated/wscript
new file mode 100644
index 0000000..c0466cd
--- /dev/null
+++ b/tests-integrated/wscript
@@ -0,0 +1,25 @@
+# -*- Mode: python; py-indent-offset: 4; indent-tabs-mode: nil; coding: utf-8; -*-
+
+from waflib import Utils
+
+top = '..'
+
+def build(bld):
+    unittests = bld.program (
+        target="../integrated-tests",
+        features = "cxx cxxprogram",
+        source = bld.path.ant_glob(['**/*.cpp'],
+                                   excl = ['**/*-osx.cpp', '**/*-sqlite3.cpp']),
+        use = 'ndn-cpp-dev',
+        install_path = None,
+        )
+
+    if Utils.unversioned_sys_platform () == "darwin":
+        unittests.source += bld.path.ant_glob('**/*-osx.cpp')
+
+    # In case we want to make it optional later
+    unittests.source += bld.path.ant_glob('**/*-sqlite3.cpp')
+
+    if bld.env['WITH_PCH']:
+        unittests.pch = "test-all.hpp"
+