Merge branch 'release/0.1.3'
tools/pipbot: Add 'sloccount' command

Issue #178.
build/tools: Install pipbot binary

Issue #178.
tools/pipbot: Remove 'wtf' command

Issue #178.
tools/pipbot: Add 'build summary' command

This supersedes the wtf command.

Issue #178.
configure: Set a default PREFIX

We want PREFIX to default to the user's ~/.local directory, since we
don't want to use /usr/local as that'll mean we need sudo permissions to
install.

Issue #178.
tools/pipbot: Rename is_number() to is_int()

Issue #178.
tools/pipbot: Add a 'show' command

Issue #178.
tools/pipbot: Make build_target() toplevel

Issue #178.
Merge branch 'feature/178'
tools/pipbot: Support quietly executing commands

This allows us to invoke shell commands silently, piping output to
/dev/null.

Issue #184.
tools/pipbot: Add a perform_action() function

This is a wrapper around run() which executes a shell command, but
accepts a human-readable string explanation for the for action that is
being performed, and prints this, rather than echoing the command.

Issue #184.
tools/pipbot: Use perform_action() in build

This silences normal execution output of the build command.

Issue #184.
tools/pipbot: Use perform_action() in deploy

This silences normal execution output of the deploy command.

Issue #184.
tools/pipbot: Use perform_action() in undeploy

This silences normal execution output of the build command.

Issue #184.
Merge branch 'feature/184'
tools/pipbot: Fix usage check in release command

Pipbot will now give you usage instructions if you don't give a valid
command.

Issue #178.
tools/pibpot: Remove unused variable

Issue #178.
tools/pipbot: Rename 'new' command to 'start'

Issue #185.
tools/pipbot: Move usage check into start()

Issue #185.