Populate Makefile with more refined targets.

* Rename `style` target to `check`.
* Split `check` to multiple subtargets.
* Factor execute flag check into separate script.
* Factor jshint check into separate script. Use standard file for
  JSHint configuration.
* Factor new line check into separate script.
* Factor pylint check into separate script.
* Add `unittest` target. Restrict it to the tests available in the
  test folder.
* Do not clutter Travis output with make commands.
* Test for available command using POSIX-compliant `command -v`.
* Do not check for executable JS inside ./node_modules.
Remove redundant files.

* checkstyle.sh replaced by separate scripts.
* DB resides in the db/ folder.
* util/ is not a python directory.
Remove execute flag from various feature files.
Merge pull request #891 from Renelvon/makefilefy

Refine Makefile
removed press from readme
Merge pull request #1002 from SamPatt/press_removed

removed press from readme
Extract interfaces out of routing table classes using abc module

fix
Add tests for data_uri module

Address reviewer comments
Merge pull request #996 from carolinux/cleanup-routingtable

Cleanup routingtable
Merge pull request #947 from carolinux/improve_test_coverage

Improve python test coverage
Use isinstance instead of comparing types.

* This is more idiomatic Python and prevents failure in case of
  subclassed types.
Use set literals.
Drop redundant len in boolean contexts.
reuse CryptoPeerConnection objects instead of always creating new ones

Signed-off-by: Thomas Stilwell <stilwellt@openlabs.co>
Merge pull request #950 from Renelvon/modern2

Use forward-compatible python (part 2)
Merge pull request #1006 from benemorius/peerconnection-reuse

reuse CryptoPeerConnection objects (too-many-files bug hotfix)