Add powerline separators anti-aliasing FAQ
Use relative links in README whenever it is possible
Move layer images into img directories
Add note on emacs-mac-port server behavior in README
Fix duplicated battery info in mode-line
Improve battery text info and faces
bind SPC TAB to alternate-buffer
Minor table reformating in documentation
Minor change to battery info
Rename config-system.el to configuration-layer.el
Random selection of startup banner
Add a templare for layer README
Update CONTRIBUTE.md for banner submission and layer readme template
Add variable dotspacemacs-startup-banner

To choose between:
- random for randomly chosen banner
- an index for a specific banner
- nil for no banner at all
Remove Ensime from company-mode-excluded-packages

Resolves #305
Better detection of battery absence
Display chosen banner in Messages
Merge branch 'develop' (v0.39.0)