Improve social icons on hover styles

Fix #90
Keep social icons small so that they are not distracting

Fix #90
Fix #102 titles are not justified in the list on tags, categories and archives pages
Remove span around timestamp

Update #102
Use em instead of px to set width of timestamp

Update #102
Use arrows instead of « and » in next previous article because they are more obvious
Merge branch 'master' into calf