Don't show '//' when using path separator

Currently, the cwd segment is showing //etc when we are in /etc and / when we are in the root file.
This small patch fix this
Fix display for home directory
Add Meslo fonts to the fontconfig file
New fixed segment showing position of current view

Solves #539
Fixed version of #540 and #579
Works now for split windows and wrapped lines.
Replace POWERLINE_OLD_PROMPT_COMMAND with the code used by [z][1]

Does not fix anything, but is three lines less and is probably the way other 
tools expect us to do.

[1]: https://github.com/rupa/z
Replace `jobs` with `jobs -p`


If some long shell code is run in the background it may be shown as more then 
one job:

    bash-4.2$ {
    > echo abc | while read line ; do
    > sleep 1s
    > sleep 1s
    > done
    > } &
    [1] 9401
    bash-4.2$ jobs
    [1]+  Running                 { echo abc | while read line; do
        sleep 1s; sleep 1s;
    done; } &

`jobs -p` print exactly one job in this case.
Document problem found when exploring #749
Fix functional shell tests in travis

Hostname in travis contains random numbers meaning that it occasionally may 
contain a PID as well. Thus it must be replaced first.
Merge pull request #754 from ZyX-I/improve-bash-bindings

Improve bash bindings
Add powerline/bindings/fish/powerline.fish
Make fish bindings feature complete, add documentation

Added features:
- Updating TMUX_PWD_* when PWD variable changes
- Updating TMUX_COLUMNS_* when WINCH signal is received
Add support for number of jobs to fish bindings
Merge branch 'develop' into feature/539-position-segment
Small fixes for new position segment

- use vim_funcs
- use a dictionary instead of a tuple for translation strings
Fix the identation of 10-powerline-symbols.conf
Merge pull request #729 from bricewge/develop

Add Meslo fonts to the fontconfig file
Add fish tests
Fix Syntastic deprecation warning

`hasErrorsOrWarningsToDisplay` has been deprecated in Syntastic.
See: https://github.com/scrooloose/syntastic/commit/d629be9

This fixes the warning that appears when opening a new file:
"syntastic: warning: function hasErrorsOrWarningsToDisplay() is
deprecated, please use !isEmpty() instead"
Merge pull request #759 from fitztrev/syntastic-errors

Fix Syntastic deprecation warning
Improve test_shells/test.sh:

- Add argument that makes it run only one shell
- Make this argument also force skipping removal of tests/shell directory
- Make it copy logs to tests/shell before and after processing