hg: improve untracked files detection (speed)
hg: refactor outgoing commits counting

Rename variable 'has_commit' to 'commits' and declare it as integer.
hg: improve speed of check for uncommitted stuff
hg: minor code layout
hg: remove usage of tail+awk in favor of sed
Merge branch 'refactor/hg-cleanup' into develop

Cleanup _lp_hg_branch_color implementation for improved speed.
Quote $LP_MARK_DEFAULT to avoid problem with space.
Rename misnamed local variable.
Respect the _lp_battery API.
Replace "pmset -g batt" parsing.
Reduce the verbosity of git calls.
has_commit is an integer.
implementing issue #110

as the activation of GIT_PS1_SHOWUPSTREAM option does for __git_ps1
the _lp_git_branch_color now compute how many commit we are ahead or
behind of our remote reference.