Integrate WeblogNG logo into header. Scales 150px asset to 96x25 px.
Align colors used for 'WeblogNG' with logo / colors from www site.
Link WeblogNG logo to www; introduce 'Blog Home' in nav bar so folks can get back to blog's index.
Merge branch 'issue-264-add-logo-to-blog'

Resolves weblogng-ui issues #264, #263