Remove unused stuff.

Clean up stuff not needed for Linux VMs:
 - remove dropbox references
 - remove OS X and Windows stuff
 - remove misc packages
Add clear-log function.
Misc settings.

 - allow tabs for indent
 - alias 'exit-emacs'
 - enable hl-line-mode in Occur buffers
Add project and other packages.

Add el-get packages:
 - projectile
 - helm
 - flx
 - logj-mode