add a link to the github issues page in the footer
add the jetbrains logo to the sponsors pages
a few small tweaks to some other logos
increase the size of the speaker icon on the session details

I've also increased the size of the speaker name, as it looked too small next to a larger icon.
Merge pull request #49 from adrianbanks/issues/38

Fix #38: add the JetBrains logo to the sponsors pages
change divs to h*
make the dashes longer
remove some specific classes and use the semantic markup for selectors
optimise the images
remove the background color and re-optimise
re-optimise the skillsmatter logo with the logo centred
prepend the @ symbol to the textbox
Merge pull request #50 from adrianbanks/make-speaker-icons-bigger

Increase the size of the speaker icon on the session details
Merge pull request #48 from adrianbanks/issues/44

Fix #44: add a link to the github issues page in the footer
Merge branch 'optimise-images' of git://github.com/adrianbanks/dddeastanglia into adrianbanks-optimise-images

Conflicts:
	DDDEastAnglia/Images/sponsors/skillsmatter.png

I resolved this in the only way that was offered: adding the file to the
index and continuing the rebase. The image may be out of date.
Merge pull request #55 from adrianbanks/issues/43

Fix #43: Prepend the @ symbol to the textbox
Add JetBrains logo to the project.

It won't display on the staging and production sites if it's not included
in the project, as it's not then included in the deployment package.