Little code and dependencies improvement in configure.sh

 The package 'build-essential' depends on the package 'gcc' and 'g++'.
indentation error in tests/test_datastore.py
Merge pull request #1106 from davalb/c0330-fixes

C0330 compliance (wrong indentation)
Merge pull request #1114 from abderraouf-adjal/patch-3

Little code and dependencies improvement in configure.sh
C0103 fixes for local variables

bug fixes

- syntax error in ws.py 309 fixed
- syntax error in dht.py 353 fixed
- using exc variable for all exceptions
- using dict literal in openbazaar_demon.py 207
- replaced verification-var where it was unnecessary

fixed undefined variable bugs in dht.py

reverted the change of the findID-attribute of the DHTSearch class

fixed TypeError: initialize() got an unexpected keyword argument 'db_connection'
Merge pull request #1107 from davalb/c0103-fixes-1

C0103 fixes 1
Clean (3) installers/ubuntu/build

Clean installers/ubuntu/build;

pull #1113 two commits is one now.
Merge pull request #1126 from abderraouf-adjal/patch-3

Clean (3) installers/ubuntu/build
c0103 changes to constants

Conflicts:
	node/dht.py

fixes

will squash this later

missing import
Merge pull request #1108 from davalb/c0103-fixes-2

C0103 fixes 2
c0103 changes in kbucket, dht and routing_table

Conflicts:
	node/dht.py
	node/market.py
	node/routingtable.py
	tests/test_kbucket.py