Added two themes

- Raven (for Dark colorschemes)
- Silver (for Light colorschemes)
README: fix link to powerline font install docs
Added theme support for console vim

- Both themes (raven and silver) have been updated
Merge pull request #613 from meonkeys/patch-1

README: fix link to powerline font install docs
Merge pull request #582 from Pychimp/two-themes

Added two themes
Update raven.vim

- Fixed the incorrect cterm background value for airline_warning
Merge pull request #614 from Pychimp/two-themes

Update raven.vim
Display warnings only when there are no errors messages.

In large code base, typically there will lot of warnings because the
file has been changed by many people and not everyone bothered to follow
coding conventions. So its more useful to show the errors first. Once
all errors have been fixed, we can focus on warnings.
themes: fix GUI murmur theme.
Make tabline's left separators customizable as right separathers.
Merge pull request #619 from bchretien/master

themes: fix GUI murmur theme.
Merge pull request #622 from spacelis/master

Make tabline's left separators customizable as right separathers.
add small section about performance to readme
Merge pull request #618 from rkannan82/master

Display warnings only when there are no errors messages.
Theme kalisi: Added 256 term colors, several changes

Changed insert mode color 3
Changed tabline modified
Changed inactive modfied statusline
Refined visual and replace mode colors
Exclude INFO from error/warning count.

Eclim uses signs for code reference searches and they shows up as INFO
signs. These are not errors/warnings and hence should not be included in
count.

Testing:
Verified the right count shows up.
Merge pull request #628 from freeo/master

Theme kalisi: Added 256 term colors and several changes
Merge pull request #631 from rkannan82/master

Display warnings only when there are no errors messages.
detect changes to tabline config variables after init. resolves #636
refactor builder and reduce state across multiple calls