Use = instead of == when running as sh

= is the POSIX equality test in shell script; when running as `/bin/sh`,
it's enough to cause problems.
Merge pull request #38 from kisom/master

Use = instead of == when running as sh
Change cover to title-page in presentation

reveal-js' macros changed to use title-page instead of cover.
Merge pull request #39 from kisom/patch-1

Change cover to title-page in presentation
Fix documentation and otp.mk rules.
Use /bin/bash explicitly to run all scripts.

On some systems /bin/sh points to a minimal shell that can't run bash
scripts.

E.g. on Ubuntu /bin/sh is a link to /bin/dash that fails to run lfetool
in some cases:

$ lfetool repl

/usr/local/bin/lfetool: 1134: shift: can't shift that many

Switching to /bin/bash fixes the problem.
Merge pull request #40 from ska80/dev

Fix documentation and otp.mk rules.
Lots of improvements to Makefile stuff.

The biggest ones are:
* fixing the OTP make targets
* adding missing vars
* moving make includes into their own dir