Update README to clarify rules about stdout/sterr

A short note in the README to explain that users should not write anything
to stdout outside of @test, setup or teardown functions.

Also added a link pointing to the wiki where more information is given
about how Bats evaluates test files.
Reorganize the readme
Emit ANSI escape sequences directly instead of calling tput
Merge pull request #26 from sstephenson/ansi

Emit ANSI escape sequences directly instead of calling tput
Remove defunct comment-pad trimming
Skip pretty formatting if the first line isn't a TAP plan

Closes #21
Bats 0.3.1
Hook up Travis CI
Log the full stack trace when a test fails
Merge pull request #25 from sstephenson/stack-trace

Log the full stack trace when a test fails
Revert "Merge pull request #25 from sstephenson/stack-trace"

This reverts commit 07bdee33a11fe790e7fcd78f1034ce086a603509, reversing
changes made to c36ad10d8c4b7f980b2965de5499257de7c07816.
Revert "Revert "Merge pull request #25 from sstephenson/stack-trace""

This reverts commit cb658ba91ff53378bac2bfa0405f0026965c3d19.
Prefer `let x+=1` for incrementing counters

The `((x++))` syntax is shorthand for `let x++`. According to `help let`:

    If the last ARG evaluates to 0, let returns 1; 0 is returned
    otherwise.

Thus the exit status of the expression `x=0; let x++` is 1, since the post-increment `++` operator evaluates to the value of the variable before incrementing.

In Bash 4, this non-zero exit status properly triggers `set -e`'s error trap, but in Bash 3 it does not. That's why the tests were passing on OS X (Bash 3) but not Linux (Bash 4).

We can work around the problem by choosing an incrementation expression that never evaluates to 0, such as `+=` or the pre-increment `++` operator. For consistency and clarity, I've changed to `x+=1` everywhere.

Ref. #25, #27
Correctly log errors in `setup` and `teardown` functions

Fixes #30
Simplify test names
Remove unused variable
add Manpages

- add bats.1
- add bats.7
- tweak install.sh to install manpages
Update the man pages
Add makefile for man pages
Ensure $PREFIX/share/man/man{1,7} directories exist

Fixes #33