Create the concept of enabled plugins

This allows users to disable a plugin without completely removing it.
Instead, they simply remove the `plugins/enabled/*.bash` file for the
plugin they want to disable.  This continues the concept of "everything
on" while providing greater flexibility to future users.

It might be a good idea to allow turning these off by default in the
future and allowing not only the `plugins/enabled/*.bash` files but also
an array of `<plugin_name>` values that would search for
`plugins/available/<plugin_name>.plugin.bash` to enable them.  That
method would make it easier for people custom tune their plugins from
within their `.bash_profile` script.

plugins/available/git.plugins.bash

@@ -0,0 +1,95 @@
+#!/bin/bash
+
+function git_remote {
+  echo "Running: git remote add origin ${GIT_HOSTING}:$1.git"
+  git remote add origin $GIT_HOSTING:$1.git
+}
+
+function git_first_push {
+  echo "Running: git push origin master:refs/heads/master"
+  git push origin master:refs/heads/master
+}
+
+function git_remove_missing_files() {
+  git ls-files -d -z | xargs -0 git update-index --remove
+}
+
+# Adds files to git's exclude file (same as .gitignore)
+function local-ignore() {
+  echo "$1" >> .git/info/exclude
+}
+
+# get a quick overview for your git repo
+function git_info() {
+    if [ -n "$(git symbolic-ref HEAD 2> /dev/null)" ]; then
+        # print informations
+        echo "git repo overview"
+        echo "-----------------"
+        echo
+
+        # print all remotes and thier details
+        for remote in $(git remote show); do
+            echo $remote:  
+            git remote show $remote
+            echo
+        done
+
+        # print status of working repo
+        echo "status:"
+        if [ -n "$(git status -s 2> /dev/null)" ]; then
+            git status -s
+        else
+            echo "working directory is clean"
+        fi
+
+        # print at least 5 last log entries
+        echo 
+        echo "log:"
+        git log -5 --oneline
+        echo 
+
+    else
+        echo "you're currently not in a git repository"
+
+    fi
+}
+
+function git_stats {
+# awesome work from https://github.com/esc/git-stats
+# including some modifications
+
+if [ -n "$(git symbolic-ref HEAD 2> /dev/null)" ]; then
+    echo "Number of commits per author:"
+    git --no-pager shortlog -sn --all
+    AUTHORS=$( git shortlog -sn --all | cut -f2 | cut -f1 -d' ')
+    LOGOPTS=""
+    if [ "$1" == '-w' ]; then
+        LOGOPTS="$LOGOPTS -w"
+        shift
+    fi
+    if [ "$1" == '-M' ]; then
+        LOGOPTS="$LOGOPTS -M"
+        shift
+    fi
+    if [ "$1" == '-C' ]; then
+        LOGOPTS="$LOGOPTS -C --find-copies-harder"
+        shift
+    fi
+    for a in $AUTHORS
+    do
+        echo '-------------------'
+        echo "Statistics for: $a"
+        echo -n "Number of files changed: "
+        git log $LOGOPTS --all --numstat --format="%n" --author=$a | cut -f3 | sort -iu | wc -l
+        echo -n "Number of lines added: "
+        git log $LOGOPTS --all --numstat --format="%n" --author=$a | cut -f1 | awk '{s+=$1} END {print s}'
+        echo -n "Number of lines deleted: "
+        git log $LOGOPTS --all --numstat --format="%n" --author=$a | cut -f2 | awk '{s+=$1} END {print s}'
+        echo -n "Number of merges: "
+        git log $LOGOPTS --all --merges --author=$a | grep -c '^commit'
+    done
+else
+    echo "you're currently not in a git repository"
+fi
+}
+